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Revision Date: 11/02/2020

NATIONAL SLATE ASSOCIATIONSLATE ROOFING GUIDE SPECIFICATION

Preface/Instructions to Designer: The following slate roofing guide specification follows the MasterSpec format and is intended to be included with other sections for related work. This document references pages in Slate Roofs: Design and Installation Manual, 2010 Edition, and Technical Bulletins, both of which are published by the National Slate Association (NSA) and available on the NSA website: www.slateassociation.org. Such references are in the following format and are shown in blue: (p.#) or (Technical Bulletin #).

In many paragraphs, the designer is required to make choices (shown in a red font) from the selections offered, or replace those with selections specific to the particular design requirements of the project. See the pages referenced in Slate Roofs: Design and Installation Manual for guidelines on making the necessary choices. Any items that do not pertain to the particular project should be deleted. Explanatory notes (shown in a green font) are offered to guide some of the choices. Explanatory notes should be deleted from your final specification.

Note that the designer of the roof is referred to as the “Design Professional” throughout this Guide Specification. “Architect,” “Engineer,” “Roof Consultant,” “A/E,” or other such professional designation may be substituted as appropriate. Similarly, the slate shingle installer is generally referred to herein simply as the “Contractor.” Other designations, such as “Roofing Contractor,” or “Installer” may be substituted as appropriate.

Lastly, although some mention is made to random width roofs, graduated roofs, and slate shingle repair herein, the underlying basis for this specification is a Uniform slate roof on a slope of 8:12 or more in which the slate shingles measure a nominal 1/4”-3/8” in thickness. In time and upon receipt of feedback concerning this guide specification, NSA may issue separate guide specifications for graduated slate roofs and slate roof repair projects. In the meantime, the specifier is encouraged to seek out additional information contained in Slate Roofs: Design and Installation Manual pertaining to, not only graduated and random roofs, and slate repair, but also on modifying this specification to better accommodate less common conditions such as: roof slopes less than 8:12, concentrated flows of rainwater, slate shingles that measure 1/2” or more in thickness, swept eaves, turrets, eyebrow dormers, canoe valleys, slate wall cladding, batten and counter-batten type installations, and a host of other special installations. ---------------------------------------------------------------------------------------------------------------------------------------------------

PROJECT NAME SECTION 073126PROJECT LOCATION PAGE 1 of 31

SECTION 073126 SLATE SHINGLES

PART 1 – GENERAL

1.1 RELATED DOCUMENTS

A. Drawings and general provisions of Contract, including General and Supplementary Conditions, and Division 0 and Division 1 Specification Sections, apply to this Section.

1.2 SUMMARY

A. Provide all labor, equipment, materials and services required to perform the work of this Section as indicated on the Drawings and specified herein.

B. This Section includes, but is not limited to, the following:

1. Installation of new slate shingles.

1. Removal of existing slate shingles and installation of new slate shingles.

1. Repair of existing slate shingles.

2. Installation of new underlayments.

3. Installation of new mitered [saddle] [Boston] [fantail] [other] hips.

4. Installation of new saddle [strip saddle] [comb] [other] ridges.

5. Such other Work as specified herein or shown in the Drawings.

C. Related Sections:

1. Section 061053 – Miscellaneous Rough Carpentry

2. Section 076200 – Sheet Metal Flashing and Trim

3. Section 077253 – Snow Guards

4. Section 264113 – Lightning Protection for Structures

1.3 REFERENCES AND STANDARDS (p.15-17, 264-267)

A. Comply with applicable requirements of the most recent editions of the following standards and others referenced in this Section. Where these standards conflict with other specified requirements, the most restrictive requirements shall govern.

1. National Slate Association – Slate Roofs: Design and Installation Manual, 2010 Edition.

2. ASTM C406 – Standard Specification for Roofing Slate.

3. ASTM D226 – Standard Specification for Asphalt-Saturated Organic Felt Used in roofing and waterproofing.

4. ASTM D4869 – Standard Specification for Asphalt-Saturated Organic Felt


Underlayment Used in Steep Slope Roofing.

5. ASTM D1970 – Standard Specification for Self-Adhering Polymer Modified Bituminous Sheet Materials Used as Steep Roofing Underlayment for Ice Dam Protection.

Note to Specifier: Currently (as of 2019), there are no ASTM standards specifically for synthetic (non-organic) roof underlayments. All underlayments, including synthetic underlayment products, are required by the International Building Code/International Residential Code to comply with ASTM D226 or ASTM D4869. In addition to these ASTM standards, jurisdictional code approvals may require an International Code Council Evaluation Service (ICC-ES) product evaluation report, for the specific synthetic underlayment product proposed.

6. ASTM E108 / UL 790 - Standard Test Methods for Fire Tests of Roof Coverings.

Note to Specifier: It is essential to verify applicable jurisdictional code versions, as there have been multiple code changes in Class A fire resistance requirements for slate roof coverings. Prior to the 2009 edition of the International Building Code (IBC), slate roof coverings whether installed over combustible or non-combustible roof decks, qualified as a Class A fire rated roof assembly (per ASTM E108 or UL 790). The 2009 edition of the IBC eliminated that language and subsequently required all roof coverings (including natural slate) to demonstrate their Class A fire resistance by utilizing ASTM or UL compliant fire testing, if the coverings are to be installed over combustible roof decks (e.g., wood). Consequently, both the 2009 and 2012 editions of the IBC require “alternative approval provisions” in accordance with IBC Section 104.11, allowing code officials to accept alternative materials not specifically addressed in the code, when presented with supporting fire resistance data (such as that found on NSA’s website, www.slateassociation.org). In 2010, the NSA and NRCA tested slate for a Class A fire resistance rating, in accordance with UL 790 criteria. The Class A rating was obtained and, consequently, the 2015 IBC code (and beyond) was amended to re-incorporate the prescriptive acceptance of natural slate as a Class A material over combustible roof decks.

7. ASTM E96 – Standard Test Methods for Water Vapor Transmission of Materials.

Note to Specifier: Verifying the permeability of all underlayment products is an essential design consideration.

8. ASTM D3161 – Standard Test Method for Wind-Resistance of Steep Slope Roofing Products.

9. FM Approvals 4473 Impact Resistance Testing of Rigid Roofing Materials by Impacting with Freezer Ice Balls. (For projects requiring FM approvals)

10. FM Approvals 4475, Class 1 Steep Slope Roof Covers, Section 4.1.1 – Approved Wind Speed Categories for Roof Covers. (For projects requiring FM approvals)

11. Florida Building Code, Chapter 15 Roof Assemblies and Rooftop Structures. (For projects requiring Florida Building Code compliance)

1.4 SUBMITTALS

A. Submittals shall be made in accordance with Section 013300.

B. Product Data

1. Underlayment(s) and underlayment fasteners. Product data for the roof underlayment must include the ASTM Standard to which it complies.


2. Slate shingles and slating nails.

3. ASTM C406 test results for specified slate (including ASTM C120, Flexure Testing of Slate (Breaking Load), ASTM C121, Water Absorption of Slate, and ASTM C217, Weather Resistance of Slate).a. Testing must be conducted in accordance with the most recent version of these

standards. b. Test results must be less than 2-years [3-years] old and be conducted on slate from

the quarry from which the slate is to be obtained [from the quarry listed in the Letter of Confirmation - see subparagraph 5, below]. (Note to Specifier: Project-specific test results (i.e., test results for the actual slate to be delivered to the job site) may be stipulated for larger projects or when imported slate is being considered. Project-specific test results should be submitted, reviewed, and approved prior to shipment of the slate to the job site.)

c. Testing shall be conducted by and reported on the letterhead of an NSA approved testing laboratory – see NSA’s website, www.slateassociation.org for approved labs.

4. Certificate of Origin for each type of slate to be delivered to the job site, identifying the country in which the slate shingles were quarried.

Note to Specifier: A Certificate of Origin is a legal trade document required for the import or export of goods across North American and international borders. It is normally only necessary in circumstances where there is a concern as to the country of origin of the slate.

5. Letter of Confirmation: Note to Specifier: The Certificate of Origin specified in subparagraph 4, above, states only the country of origin of the slate being shipped. As such, if the slate’s original point of origin is of concern, the Specifier should also ask for Letter of Confirmation from the quarry/distributor certifying that slate being provided was produced in the country, region, and/or quarry specified in Part 2 of this Section. This would also further confirm that a domestic product is being provided, if in fact a domestic slate is specified in Part 2. A Letter of Confirmation is prudent when there is concern that an imported slate is being marketed as a North American slate.

Note to Specifier: North American roofing slate has a long history of outstanding service and has been tested in accordance with the above-mentioned ASTM Standards for decades. When considering the specification of non-North American slate, the specifier should: a) query the quality control standards of non-North American suppliers, b) scrutinize the proposed slate by reviewing ASTM test results, Certificates of Origin, Letters of Confirmation, and samples prior to specifying the slate, and c) work with a reputable North American supplier/distributor. In addition, the specifier should obtain from the supplier/distributor a guarantee, in writing, stating that the slate to be provided will be free of inclusions of oxidizable iron pyrite and is appropriate for use in North America. The specifier may also request, as further product quality confirmation, test results that indicate the slate to be provided complies with the standards of the country of origin, or if that country has no standards, with the European Union (EU) Standard, as well as the aforementioned ASTM test results.

C. Samples

1. Three to five slate shingles of each color, showing the full, natural range of color variation to be expected in the finished work.a. For uniform slate roofs, submit sample slates of size specified herein, with nail holes

punched [drilled].a. For random-width/graduated slate roofs submit sample slates of representative

sizes, with nail holes punched [drilled].

2. Slating nails, showing the full range of sizes required.

3. Slate hooks.


4. Slate repair materials.

D. Shop drawings

1. Scaled drawings showing all shapes, sizes, and colors of slate for all patterns, designs, images, figures, numbers, and letters to be incorporated into the slate shingles, including information on method(s) of attachment.

1.5 QUALITY ASSURANCE

A. Work of this Section shall comply with applicable standards indicated or implied.

B. Provide products in each color from a single quarry during the course of the Work for consistency of quality and appearance.

C. Slate roofing contractor shall be a member in good standing of the National Slate Association, www.slateassociation.org.

D. Slate roofing contractor shall have at least 10-years experience in the installation of new slate roofing/repair of existing slate roofing and shall have successfully completed at least three slate roofing projects within the past five years similar in scope and scale to the Project specified herein. Foreman or superintendent shall have similar experience and shall provide full-time supervision of installers.

1.6 TEST/MOCKUP PANELS

A. Prepare the following slate roofing test/mockup panels in an area and size designated by the Design Professional, or as indicated below, to verify selections made under sample submittals and to demonstrate aesthetic effects and quality standards of materials and execution.

Note to Specifier: For the purposes of this Guide Specification, “Test Panel” refers to examples of the work laid out and installed on the finished roof deck (i.e., in-situ). Test panels are sometimes referred to as “in-situ mockups.” They are brief pauses in the Work that allow the Design Professional to assess the detailing, craftsmanship, character, and quality of relatively small areas of Work prior to the Contractor undertaking much larger areas/quantities of similar Work. Test panels allow the Contractor to demonstrate that the Work can be executed in accordance with the Contract Documents. If approved, test panels typically remain in place and become a part of the completed roof system. “Mockup Panels” are similar to test panels, except that the sample areas are installed on separately constructed, full-scale, models, representative of the roof areas actually on the building. Mockup panels are generally executed prior to the start of actual construction on the building. If mockups are desired, the Specifier should specify the size and extent of the mockup panel. Because they require the construction of model roof areas, mockup panels are typically more expensive than test panels. If test panels are preferred, the word “mockup” can be eliminated from the title of this Article, and vice versa. Going forward, this Article will address “test panels” only.

Test panels should incorporate the basic details of installing a slate roof, including details for underlayment, ice dam protection membrane, drip edges, cant strips, slate sorting and blending, starter slates, headlap, offset, joint spacing, nailing, approach slates and finishing slates.

Test panels should also demonstrate the treatment of any consistent or repetitive details in the finished roof, including details for changes in roof pitch, swept eaves, hips, ridges, valleys, and dormer work.

Of the test panels listed below, delete those that do not apply and insert others that are desired, but not listed.

1. Installation of slate shingles at roof eave (starter, first, second, and third course), including underlayments, drip edge metal, and cant for slate, 5 linear feet.


2. Installation of slate shingles at open/closed valley, 3 to 4 courses at 1 valley.

3. Approach slates at a rake, 3 to 4 courses.

4. Slate shingles adjacent to a vertical wall (including base/step flashings), 3 to 4 courses.

5. Approach slates at a ridge, 3 to 4 courses x 5 to 8 linear feet.

6. Slate shingles at the change in roof plane, 5 to 8 linear feet.

7. Slate shingle roofing, 100 to 200 square feet.

a. This test panel shall be completed only after the test panels listed above in subparagraphs 1, 2, 3, and 4 are reviewed and approved by the Design Professional.

8. ____ (insert type of hip; e.g., mitered) hip slates, 3 to 4 linear feet of hip.

9. ____ (insert type of ridge; e.g., saddle) ridge slates, 3 to 4 linear feet of ridge.

B. Modify test panels as required to produce acceptable work in compliance with this specification and meeting the approval of Design Professional.

C. Do not proceed with remaining work until test panels are approved, in writing, by the Design Professional.

1. Approved test panels shall be left in place and incorporated into the final construction.

D. Approval of test panels does not constitute approval of deviations from the Contract Documents contained in the panels, unless such deviations are specifically approved, in writing, by the Design Professional.

E. Coordinate test panels specified herein with each other and with those specified in other sections as required.

F. Group test panels to the maximum extent possible such that Design Professional may review multiple test panels from this and other specification sections in the course of a single site visit.

1.7 DELIVERY, STORAGE, AND HANDLING (p.18)

A. Ensure the availability of adequate off-loading equipment and manpower at the job site for the mode of delivery used, and storage space for the quantity of slate shingles to be received.

B. Deliver slate shingles to project site in quarry crates/pallets with each labelled with the source, country of origin, size, quantity and color contained in each pallet.

C. Slate shingles shall be packaged on edge and separated by wood lath or other rigid material if rows are stacked vertically in the crate/pallet.

D. During extended periods of storage on site, tarp or otherwise cover the pallets/crates to keep the shingles clean and prevent them from freezing together during cold weather.

E. Store crates/pallets at site on a solid, level surface and handle shingles to prevent chipping breakage, soiling or other damage.


F. Load slate shingles on the building in a manner to avoid damage to the roof deck, structural supporting members, staging and scaffolding.

G. Store accessory materials including nails, slate hooks, underlayment, and ice dam protection membrane according to the manufacturer’s recommended storage instructions.

1.8 PROJECT/SITE CONDITIONS

A. Prior to beginning work, Contractor shall secure approval from the Owner [Design Professional] for the following:

1. Areas permitted for personnel parking.

2. Access to the site and hours for construction activity.

3. Areas permitted for storage of materials and debris.

4. Areas permitted for the location of cranes, hoists, and chutes for loading and unloading materials to and from the roof.

B. Interior stairs or elevators may [may not] be used for removing debris or delivering materials to the roof or ground.

C. Contractor employee access shall [shall not] be permitted to the interior of the building. Building access approval shall be obtained from the Owner [Owner’s Representative].

D. Exterior sanitary facilities are required and shall be provided by the Contractor.

D. Contractor personnel may make use of restrooms located within the building so long as the privilege is not abused and the facilities are maintained in a sanitary condition as determined by the Owner.

E. An exterior water source and electricity shall [shall not] be provided by the Owner.

F. The buildings shall [shall not] remain occupied during construction. During the full course of the Work, the Contractor shall ensure that all pedestrian access points, including all entrances, foot paths, sidewalks, emergency means of egress, and vehicle access routes, shall be protected and display clear signage where barricades and construction fencing are employed. Do not block fire exits or impede ADA access.

G. If discrepancies are discovered between the existing conditions and those noted on the Drawings, immediately notify the Design Professional in writing and obtain written approval prior to commencing the Work. All necessary steps shall be taken to make the building watertight until the discrepancies are resolved.

H. Proceed with the Work as weather conditions permit and/or as required by manufacturer’s installation instructions or warranty requirements.

I. Proceed with slate shingle roofing installation only after substrate construction, vent stacks, and other roof penetrations are complete, when substrate materials are dry, and weather conditions are appropriate.


J. The Contractor shall ensure that work areas as well as the entire building are completely protected from water infiltration and remain watertight throughout the course of the project and water does not flow beneath any completed sections of the slate roof system.

K. The Contractor shall be responsible for replacing all broken slates on the project, prior to project closeout. After project closeout, the slate repair responsibilities of the Contractor shall be as set forth in the project contract and warranty documents.

L. All means of access required to perform the work of this Section shall be the responsibility of the roofing contractor [general contractor] [other sub-trades]. All means of roof access shall fully comply with all local, state, and OSHA safety codes and requirements.

1.9 SEQUENCING/SCHEDULING

A. Schedule and execute work to prevent leaks and excessive traffic on completed roof sections. Coordinate work of this Section with interfacing, adjoining, and related roofing work for proper sequencing of each installation.

B. Do not disrupt activities in occupied spaces.

C. At the discretion of the Owner, the project may [may not] be completed in phases.

D. When multiple trades are accessing the same work area, coordinate the work sequence so as not to hinder the project schedule or detract from the quality of the work.

1.10 WARRANTY

A. Slate Shingle Supplier Warranty: Submit slate shingle supplier warranty, signed by the supplier and covering the slate shingles described in this Section, in which the supplier agrees to replace slate shingles that fail in materials and deliver the replacement slate to the original point of destination. The duration of this warranty shall be 75 [50] [100] years from date of original supply.

Note to Specifier: Minimum warranties suggested by ASTM C406 grade classifications are as follows. Verify desired warranty period with the supplier(s) you specify herein.S1 - 75 yearsS2 - 40 yearsS3 - 20 years

B. Roofing Installer Warranty: Submit roofing installer warranty, signed by roofing installer and covering Work of this Section, in which the roofing installer agrees to repair or replace slate roofing that fails in materials or workmanship within the following warranty period.

1. Warranty Period: Two years from date of substantial completion1. Warranty Period: Five years from date of substantial completion select one1. Warranty Period: ____ years from date of substantial completion

C. Additional Roofing Installer Warranty: The roofing installer agrees to return to the job site one year from the date of substantial completion of the Work [one year to 18 months from the date of substantial completion of the work (whichever is shorter and allows one full winter season after the date of substantial completion] (Note to Specifier: This is to allow for snow-induced shedding of slates broken/cracked during installation) to replace any broken or missing slates created as a result of normal, installation-related, shedding.

1.11 EXTRA MATERIAL


Note to Specifier: Select extra material requirements with consideration for Owner’s storage capabilities.

A. Provide an additional 3 percent of installed field, starter and hip and ridge slates, but not more than one full crate/pallet in total, for Owner’s use in future roof maintenance.

A. Provide an additional 3 percent of installed field, starter and hip and ridge slates for Owner’s use in future roof maintenance

A. Provide an additional 1 percent of installed field, starter and hip and ridge slates for Owner’s use in future roof maintenance.

A. Provide an additional one square of installed field slates, twenty pieces of starter slate, and thirty pieces of hip and ridge slates for Owner’s use in future roof maintenance.

A. Provide an additional ____ pieces of installed field, ____ pieces of starter slate, and ____ pieces of hip and ridge slates for Owner’s use in future roof maintenance.

B. Place extra material in storage in a location designated by the Owner.

PART 2 – PRODUCTS

2.1 SLATE SHINGLES (p.5-17)

Note to Specifier: Natural slate is available in many colors, sizes, thickness, and shapes. This provides opportunities to create customized textures and patterns.

A. Standard: New slate shall comply with ASTM C406, Standard Specification for Roofing Slate, Grade S-1; hard, dense, and sound natural stone, with chamfered edges. No broken or cracked slates will be accepted and exposed corners shall be full [and no broken exposed corners exceeding 1”, [1½”], will be allowed]. (Note to Specifier: Clarify the tolerance for broken corners to suit specific job requirements beyond these parameters if aesthetics is a concern.) Broken covered corners shall not prevent the laying of a weathertight roof and the slate shall not be installed when either the base or leg of the right triangle broken off exceeds 2”.

1. Breakage of all kinds, including broken upper and lower corners exceeding the dimensions specified above, shall not exceed 1% in the shipment delivered to the site.

2. Acceptable suppliers include ________ and _______, or Design Professional approved alternate supplier. No substitutions.

(Note to Specifier: See NSA’s website, www.slateassociation.org, for a current list of NSA Member quarries and distributors.)

A. Reclaimed/salvaged slate shall match the color, weathering characteristics, size, and shape of the existing slate; be sound, with whole or nearly whole corners; emit a ring when tapped indicative of the shingles being free from cracks and significant delamination; possess nail holes sufficiently whole so as to provide adequate nailing strength; and have an expected remaining service life equal to that of the existing slate. Acceptable suppliers include ________ and _______, or Design Professional approved alternate supplier. (Note to Specifier: This option might be selected when a project primarily entails slate repair work and/or an addition, the roof of which is to match an existing slate roof as closely as possible.)

A. Reclaimed/salvaged slate shall be sound, with whole or nearly whole corners; emit a ring when tapped indicative of the shingles being free from cracks and significant delamination; possess nail holes sufficiently whole so as to provide adequate nailing strength; and have an expected remaining service life of _____ years. Acceptable Suppliers include ________ and _______, or Design Professional approved alternate supplier. (Note to Specifier: This option might be selected when reclaimed slate is desired primarily for aesthetic or cost reasons.)

B. Source and Color of Slate:


Note to Specifier: The following are some of the common colors, with the corresponding common names shown in parentheses. Color names often vary by quarry, making it important for specifiers to review samples to help ensure the desired color characteristics are achieved. If more than one color is to be used, specify the percentage of each color.

1. Vermont & New Yorka. Semi-Weathering Gray/Green (Sea Green)b. Semi-Weathering Gray (Vermont Gray)c. Semi-Weathering Gray/Black (Strata Gray)d. Semi-weathering Gray/Black (Mottled Gray/Black)e. Semi-Weathering Black (Vermont Black)f. Semi-Weathering Variegated Purpleg. Semi-Weathering Purple (Royal Purple)h. Unfading Mottled Green and Purplei. Unfading Gray/Greenj. Unfading Greenk. Unfading Grayl. Unfading Purple

Note to Specifier: As of 2019, Unfading Purple as produced in North America contains green inclusions with some slates being more green than purple. As of 2019, Unfading Purple slate from the Penrhyn Quarry in Wales may be the best option where clear unfading purple slates are required.

m. Unfading Red

1. Pennsylvaniaa. Fading Black (Pennsylvania Black, Pennsylvania Gray, Penn Black)

Note to Specifier: This slate is in limited production as of the revision date of this Guide Specification and is considered to be an S-2 rated roofing slate under ASTM C406, Standard Specification for Roofing Slate.

Note to Specifier: The “fading” color description above represents a change from the “semi-weathering” description contained on pages 8-9 of Slate Roofs Design and Installation Manual, 2010 Edition.

1. Virginiaa. Unfading Black (Buckingham-Virginia Black, Buckingham Black, Buckingham,

Grayson)Note to Specifier: Black colored slates from the Peach Bottom District (Pennsylvania/Maryland border) and the Monson District (Piscataquis County, Maine) are no longer quarried. In addition, Pennsylvania Black slate (see above) is, as of the revision date of this specification, in limited production. Unfading black slate from Virginia and North Country Black slate from Quebec (see below) are generally considered acceptable substitutes for these slates. Keep in mind that unfading black slate from Virginia will have somewhat more surface sheen than Peach Bottom, Monson, and Pennsylvania Black (due to the greater quantity of mica in its composition) and be a somewhat darker black color. North Country Black slate, on the other hand, will have somewhat less sheen than Peach Bottom and Monson slate and be somewhat lighter in color than Peach Bottom. In addition, North Country Black, being an unfading slate, will not develop surface markings and change color tones as the fading Pennsylvania Black does. Generally, unfading black slate from Virginia is used a substitute for Peach Bottom slate and North Country Black as a substitute for Monson and Pennsylvania Black slate. Each roof is unique, however, and, as such, samples should be requested to determine which slate will provide the best match.

1. Quebec a. Unfading Black (North Country Black)


Note to Specifier: Black colored slates from the Peach Bottom District (Pennsylvania/Maryland border) and the Monson District (Piscataquis County, Maine) are no longer quarried. In addition, Pennsylvania Black slate (see above) is, as of the revision date of this specification, in limited production. North Country Black slate from Quebec and unfading black slate from Virginia (see above) are generally considered acceptable substitutes for these slates. Keep in mind that North Country Black slate will have somewhat less sheen than Peach Bottom and Monson slate and be somewhat lighter in color than Peach Bottom. In addition, North Country Black, being an unfading slate, will not develop surface markings and change color tones as the fading Pennsylvania Black does. Unfading black slate from Virginia, on the other hand, will have somewhat more surface sheen than Peach Bottom, Monson, and Pennsylvania Black (due to the greater quantity of mica in its composition) and be a somewhat darker black color. Generally, North Country Black slate is used as a substitute for Monson and Pennsylvania Black slate and unfading black slate from Virginia as a substitute for Peach Bottom slate. Each roof is unique, however, and, as such, samples should be requested to determine which slate will provide the best match.

1. Imported (various)Note to Specifier: As of the revision date of this Guide Specification, imported slate is available primarily from Spain, China, Argentina, and Wales. Imported slate may also be available from other countries, including India, South Africa, Brazil, and Great Britain. Quality, suppliers, and distribution varies. (See Paragraph 1.4.B.3─B.5, above, for guidance when considering imported slates from outside North America.)

Note to Specifier: Imported slates may be produced to metric sizes. Some suppliers will round the metric sizes up or down and quote nominal imperial sizes. When determining the required exposure (see Paragraph 3.4.E.1, below), it is important to start with the required headlap and calculate a custom exposure using the formula Exposure = (Length - Headlap)/2. For example, for a 450 mm long slate to be laid with a 3” headlap, the exposure will be 7-3/8” ((17-3/4” - 3”)/2), 17-3/4” being the Imperial dimension closest to 450 mm. (Note; had the nominal length been used instead of the actual length, the exposure would have been 7-1/2” and the headlap only 2-3/4” (17-3/4” - 7-1/2” - 7-1/2” = 2-3/4”), and in violation of the building code. Note, as well, that a reduced exposure in applying metric slates to a 3” headlap will result in less coverage and require the ordering of additional quantities of slate, as compared to a slate produced to Imperial dimensions.

C. Shape of slate: (p.11)Note to Specifier: The standard shape for natural roofing slate is a rectangle with the long dimension laid running parallel to the slope. Slate shingles can also be supplied in special shapes with the exposed butt trimmed to dimensions specified at the time of order. More than one shape may be specified. Specifier/roof designer should provide drawings of special shapes, patterns, etc.

1. Rectangle

2. Gothic2. Clipped Corner2. Hexagon2. Fish Scale/Beaver Tail2. Diamond

D. Size: (p.12 for standard slate sizes)Note to Specifier: Imperial sizes are used in this Specification and are most common in North America. Metric sizes are available, but Specifier should not mix Imperial and metric sizes because the slight difference in dimension will affect joint spacing and headlap. Caution: Imported slate in metric sizes are sometimes marketed as nominal Imperial sizes and these metric slate are undersized relative to the true Imperial sizes and may not meet the tolerances required within this specification.


1. Length a. Single length _____”a. Staggered lengths of _____” and _____”a. Graduated lengths: from _____” to _____” (Note to Specifier: Specify percentage

of each length, or number of courses of each length)

2. Width (Note to Specifier: Standard widths are not less than ½ the length)a. Uniform width _____”.a. Random widths from ____” to ____” (Note to Specifier: Suppliers will typically

provide 3 or 4 different standard widths; Specifier should indicate percentage range for each width and should check with Supplier for availability of other blends if needed.)

b. Wider slates as needed for approach slates and slates adjacent to valleys, hips, vertical walls, rakes, etc. Wider slates shall measure ____” and ____” in width. Note to Specifier: Approach slates are installed as the Work moves toward, or approaches, a vertical surface, rake, or change in roof plane as they can help to minimize field trimming and eliminate the use of narrow (aka “sliver”) slates which can break more easily and allow for the passage of rainwater to the nail holes. Approach slates are particularly useful on Uniform slate roofs. If possible, the wider slates specified should be standard widths. That said, it is not uncommon to specify wider slates that are 2” wider than the widest standard width slate (e.g., if 14” is the widest standard width, it might be necessary to specify 16” wide slates). If a non-standard width is specified, this should be noted here in the Specification.

3. Thickness: (p.13)Note to Specifier: Standard thickness of roofing slate, today, in North America is generally considered to be nominal 1/4” or nominal 1/4” to 3/8”. Note that 3/16” thickness is no longer commonly produced.

Slate is a natural product and the term “nominal” allows or some variation in the actual thickness received at the job site. For example, if nominal 1/4” thick slate is specified, expect that the bulk of the order will consist of slates right around 1/4” thick, but that some portion of the shipment will be made up of 3/16” to 1/4” thick slates and 1/4” to 5/16” thick slate. If a very uniform and planar appearance is desired, sorting of the slate into thickness groups will assist in achieving this aesthetic (see Paragraph 3.1.C, below). If greater thickness tolerances are desired in a nominal 1/4” thick slate, specify that no slates shall be less than 3/16” nor greater than 5/16” thick, and that no more than a certain percentage of slates in the shipment (10% is a reasonable number) shall measure 3/16” or 5/16” in thickness. Be aware that the tighter the tolerances imposed, the costlier the slate is likely to be. Lastly, understand that slates are split to thickness by eye. No one at the quarry is using calipers, nor should the party(ies) receiving the slate order. For nominal 1/4” and nominal 1/4” to 3/8” slate, plus or minus 1/16” is about as tight a tolerance that can be reasonably imposed. It is not realistic to specify tolerances in the range or 1/32”, 1/64”, or hundredths of an inch. For more information, see Paragraph 3.1.E.2, below, and NSA Technical Bulletin No. 4, “Checking Roofing Slate Deliveries,” available at www.slateassociation.org.

a. Single thickness: nominal ______”a. Intermingled thicknesses: range from ___” to ___” (Note to Specifier: Go on to

specify percentage of each thickness.)a. Graduated thickness: range from ___” to ___” (Note to Specifier: Graduated

roofs can be uniform thickness or varied; if varied, specify the number of courses of each thickness or otherwise specify the quantity of each thickness.)

4. Starter slates: ____” L x ____” W x ____” Thick (p.70-71)

5. Hip slates: ____” L x ____” W x ____” Thick (p.142-157)


6. Ridge slates: ____” L x ____” W x ____” Thick (p.158-173)

E. Nail Holes: (p.17-18; also refer to Technical Bulletin #1 for drilled vs. punched nailed holes)

1. Punch or drill two nail holes in each slate, located one-quarter to one-third down the slate length, measured from the head of the slate, and 1¼” to 1½” in from each side edge. Nail holes shall be located on the thinner end of the slate. (Note to Specifier: Slates measuring more than ¾” in thickness and 20” in length require 4 nails. If this is the case, specify that the additional 2 holes be located approximately 2” above the regular nail holes.)

2. Hip, ridge, and approach slates shall [may] be supplied unpunched. These slates shall be punched or drilled on site.

3. Starter slates may be supplied punched or unpunched. If supplied unpunched, these slates shall be punched or drilled on site.

3. Starter slates shall be supplied unpunched. These slates shall be punched or drilled on site.

F. Texture of Slate: Note to Specifier: Degree of texture is dependent on each type of stone. Generally, thicker slate has more texture. For heavier texture in thinner slate, consider a mix of thicknesses, breaking corners, and/or staggering lengths. Check with the Supplier to be sure that the desired texture is available.

1. Smooth 1. Medium 1. Heavy

2.2 SLATING NAILS (p.27-28)Note to Specifier: The starting point for the slating nail specification is an 11-gauge, smooth-shank, large-head, solid copper slating nail in a length equal to twice the slate thickness plus 1”. Nail material, length, gauge, and shank type must be edited as required to fit the particular project.

A. Slating Nails shall be sharp-pointed with a 3/8-inch diameter flat head.

1. Material: Solid copper. (Note to Specifier: Solid copper nails are preferred for their longevity and ease of future slate repair work. Type 304 stainless steel and Type 316 stainless steel slating nails may be considered for hard roof decks that cause copper nails to bend. Stainless steel nails will make future slate repair more difficult. Galvanized nails are not recommended, except for short-term repair work.)

2. Thickness/Shank Diameter: 11-gauge (.120”), 10-gauge (.134”) (Note to Specifier: 10 ga. nails may be considered for hard roof decks that cause 11 ga. nails to bend.)

3. Length: Of sufficient length to penetrate a minimum of 3/4-inch into sheathing/thru plywood sheathing (typically twice the thickness of the slate plus 1-inch). (For example: for 1/4”-3/8” thick slate, specify 1-3/4” long nails.)

4. Shank: Smooth, annular ring (Note to Specifier: Smooth-shank nails are generally satisfactory in wood and plywood substrates and are recommended in concrete and gypsum plank substrates. Ring-shank nails are generally unnecessary for securing slate shingles and will make any future slate repairs more difficult.)

5. Hip and Ridge Slates: Insert length, gauge, and shank type. (Note to Specifier: Depending on the type of hip and ridge, specify longer nails to account for the extra


layers of slate at hips and ridge. Note, as well, that longer nails may have to be heavier gauge to avoid bending.)

6. Underside of Roof Deck Exposed to View: lnsert length, gauge, and shank type. (Note to Specifier: Where the underside of the roof deck is exposed (e.g., open rakes and soffits, porch roofs), the slating nail may penetrate through and become visible or cause the underside of the deck to splinter. In this situation, there are basically two options: 1) install supplemental roof sheathing over the entire roof slope to increase the overall thickness of the roof deck and allow the use of longer nails (be sure to check the added dead load with a structural engineer); or, 2) use shorter nails that will not penetrate through the roof deck and consider specifying ring-shank nails to enhance pull-out resistance.)

7. Gypsum/Concrete/Lightweight Concrete/Clay Tile Roof Decks (p.238): (Note to Specifier: These deck types may have particular fastening requirements. If they are nailable, smooth-shank slating nails tend to perform better, in terms of pull-out resistance, than ring-shank nails. If they are not nailable, a nailable deck may have to be provided, either on top of, or in place of the existing deck, or an alternative installation method used for the slate shingles (for example, there are several hook-type systems available, the tracks for which can sometimes be secured to the roof deck with a fastener type more suitable to non-nailable decks).

2.3 UNDERLAYMENTS (p.54, 64-69)Note to Specifier: Asphalt-saturated organic felt underlayment has traditionally been installed below slate roofing. The material is permeable (perm rating of about 5 or 6) and still widely available and used today. Numerous other types of roof underlayment, made of a wide variety of materials and possessing a wide range of physical properties, are also available in today’s marketplace. The vast majority of these so-called “synthetic underlayments” are vapor impermeable (perm ratings of 1.0, or less). As of the 2018 edition of both the International Building Code and International Residential Code, roof underlayments used in conjunction with slate roofing must comply with either ASTM D226, Standard Specification for Asphalt-Saturated Organic Felt Used in Roofing and Waterproofing, or ASTM D4869, Standard Specification for Asphalt-Saturated Organic Felt Underlayment Used in Steep Slope Roofing. As such, synthetic underlayments require an International Code Council Evaluation Services (ICC-ES) product evaluation report to confirm their compliance with one or both of these Standards since there currently (as of 2019) are no ASTM standards specific to synthetic roof underlayments. Options for both organic felt and synthetic roof underlayments are provided below. It is up to the designer of record to select a roof underlayment appropriate for a particular project. Additional information to aid in the selection of underlayment can be found below, in the National Roofing Contractor Association’s (NRCA’s) The NRCA Roofing Manual: Steep-Slope Roof Systems, NSA’s Slate Roofs: Design and Installation Manual, manufacturer’s websites, and various trade publication articles. If in doubt, it is generally prudent to use a vapor permeable roof underlayment rather than a vapor impermeable underlayment.

A. Felt: No. 30 unperforated asphalt-saturated organic felt, 36”-wide rolls complying with ASTM D226 Type II or ASTM D4869 Type IV.

Note to Specifier: Asphalt-saturated organic felt underlayments tend to wrinkle and weather when exposed to the weather and generally should not be left exposed on the roof for more than about 30 days.

1. ProductsNote to Specifier: Specific products may be listed here. The list of products below is not comprehensive. Other products may be suitable and still others may postdate the revision date of this publication. Specifier should review current product data for each product prior to specifying. NSA neither recommends nor endorses any of the products listed.

a. “Gorilla Guard Spec 30,” Atlas Roofing Corporation, Atlanta, GA 30328, (800) 251-2852

b. “#30 ASTM,” Warrior Roofing Manufacturing, Chambersburg, PA 17201, (717) 709-0323


c. “No. 30 ASTM” or “No. 30 UL,” Tamko Building Products, Joplin, MO 64802, (800) 641-4691

The above specified manufacturers, and other organic felt manufacturer’s, have other products with the phrase “#30” or “No. 30” in their name and on their label when, in fact, the felt does not weigh a minimum of 26 pounds per square as required by the above stated ASTM Standards. Some might construe these labels as misleading. It is imperative that the Contractor provide the submittals specified in Paragraph 1.4, above, to help ensure the correct underlayment is installed on the roof.

Note to Specifier: In addition to asphalt saturated organic felt, fiberglass-reinforced modified bitumen membranes complying with ASTM D226 and D4869, including Boral’s “Boral Ply 40” (www.boralroof.com) and Malarkey’s “Right Start UDL” (www.malarkeyroofing.com), are sometimes used as an underlayment below slate shingles. Please note, however, that these products have a permeance level of 0.1 perm or less and are, therefore, considered impermeable, Class 1 vapor barriers.

2. Underlayment Accessoriesa. Corrosion resistant, large head fasteners of sufficient length to prevent wind

event blow-off, or as recommended by underlayment manufacturer. (Note to Specifier: Large head roofing nails and metal or plastic cap nails may be specified. The latter generally provide greater wind uplift resistance.)

Note to Specifier: The IBC contains specific minimum fastener requirements for underlayment applied in areas subject to high wind speeds. Language consistent with Code should be inserted in lieu of the above if the project is located in an area of high wind. See, for example, Section 1507.7.3.1. of the 2015 IBC and Table 1507.1.1(3) of the 2018 IBC.

A. Synthetic Underlayment: UV resistant synthetic polymer (polypropylene, polyolefin, or polyethylene) highly vapor permeable underlayment.

Note to Specifier: Highly permeable underlays are recommended due to recent building science advances making buildings more air tight which has created some issues with moisture accumulation and deterioration in some steep-slope roof assemblies containing vapor impermeable layers. Having an underlay that allows vapor to pass through virtually unimpeded will minimize water vapor accumulation within the roof assembly over time. Some highly vapor permeable underlayments will allow liquid water passage under heavy weather conditions such as thunderstorms, so attention must be paid to the abilities, and limitations, of any product specified and the service the material is intended to provide (i.e., temporary roofing). Less permeable underlays have historically been the dominant material used in slate roofing. As discussed above, advancements in the building science of air and vapor barriers have in some instances adversely impacted steep-slope roofing assemblies when a vapor retarding underlay is installed. Vapor retarding underlays can still be used, however the designer/specifier must assess the entire roof assembly down to the occupied space (including not only the construction of the building, but also passive and active mechanical ventilation of any attic/interstitial spaces), and provide for the escape of moisture that may accumulate below an impermeable underlayment that could result in long term deterioration of the wood deck/framing.

1. Physical Propertiesa. Water Vapor Transmission: 15 perms, minimum, per ASTM E96, Method B b. Liquid Water Transmission: Pass per ASTM D4869c. Roof Assembly Fire Classification: Class A or Class B per UL 790 or ASTM E108

2. ProductsNote to Specifier: Specific products may be listed here. The list of products below is not comprehensive. Other products may be suitable and still others may postdate the revision date of this publication. Note that the products listed below may not be appropriate for all projects and that some breathable synthetic underlayments may not be appropriate for keeping a building


dried-in prior to, and while the slate is being installed. Preliminary results of testing sponsored by WSRCA suggest that some synthetic underlayments break-down sooner than their stated exposure rating (number of days before permanent roofing materials must be installed). Check with the manufacturer for installation on buildings other than those permitted by applicable code to have nonclassified roofing (i.e., materials not having a fire classification rating of A, B, or C). (Note: Section 1505 of the IBC requires that roofing materials and assemblies be tested in accordance with UL 790 or ASTM E108 in order to achieve a fire classification, not ASTM E84.) Specifier should review current product data for each product prior to specifying. NSA neither recommends nor endorses any of the products listed.

a. “SlopeShield Plus Self-Adhered,” VaproShield LLC., Gig Harbor, WA 98335, (866) 731-7663

b. “Delta-FOXX,” Dorken Systems Inc., Beamsville, ON, Canada, (888) 4-DELTA-4c. “Delta-VENT S,” Dorken Systems Inc., Beamsville, ON

3. Underlayment Accessories Note to Specifier: Some of the accessory products listed below may not be available, or necessary, for all of the synthetic roof underlayments list above in subparagraph 2. Other accessory products may be available/necessary as well.

a. Single sided tape: Tape compatible with chemistry of underlayment material installed, for use at penetrations through the underlayment and tears.

b. Double sided tape: Tape for use within horizontal and vertical seams of underlayment if it is to be used as an air barrier as well as a weather/water barrier

c. Sealant: Gun grade sealant for use at flashing penetrations in conjunction with single sided tape

d. Fasteners: Corrosion resistant, metal or plastic caps nails as recommended by the underlayment manufacturer.

Note to Specifier: The IBC contains specific minimum fastener requirements for underlayment applied in areas subject to high wind speeds. Language consistent with Code should be inserted in lieu of the above if the project is located in an area of high wind. See, for example, Section 1507.7.3.1. of the 2015 IBC and Table 1507.1.1(3) of the 2018 IBC.

B. Ice Dam Protection Membrane Self-Adhering Underlayment, [high temperature,] polyethylene faced for ice dam protection at eaves and where shown in the Detail Drawings: ASTM D 1970, minimum of 30 mils thick; slip-resistant, polyethylene-film or granule surfaced laminated to SBS-modified asphalt adhesive, with release-sheet backing; cold applied.

Note to Specifier: In the 2015 Edition of the IBC, and earlier editions, ice dam protection membrane is required at the roof eaves “in areas where the average daily temperature in January is 25oF or less or where there is a possibility of ice forming along the eaves causing a backup of water.” As of the 2018 IBC, this requirement was changed; ice dam protection membrane being required “in areas where there has been a history of ice forming along the eaves causing a backup of water.” Accordingly, the above paragraph may be retained or omitted based on local climate conditions and best practices in the geographic region where the project is located. Ice dam protection membranes designed to withstand high temperature applications are generally recommended below slate shingles given the degree to which they can heat up in direct sunlight during the summer months. For the same reason, high temperature underlayment should also be used below metal flashings.

1. ProductsNote to Specifier: Specific products may be listed here. The list of products below is not comprehensive. Other products may be suitable and still others may postdate the revision date of this publication. Specifier should review current product data for each product prior to specifying. NSA neither recommends nor endorses any of the products listed.

a. “Grace Ice & Water Shield HT,” GCP Applied Technologies, Inc., Cambridge, MA 02140, (617) 876-1400 or (877) 423-6491

b. “WeatherLock G,” Owens Corning, Toledo, OH 43659, (800) 438-7465

2.4 ACCESSORIES (p.24, 70, 213-219)


A. Slate hooks for slate repair work: For slates with a 3” headlap and measuring up to ¾” thick, 3” long, 10-gauge, solid copper, Type 304 stainless steel, or Type 304 stainless steel powder coated black or bronze with 3/8” hook or 3/4” hook.(Note to Specifier: Slate repair hooks are available in two standard sizes: 3/8” to accommodate slates up to 3/8” thick and 3/4” to accommodate slates from 1/2” -3/4” thick.)

1. Custom slate hooks for headlaps greater than 3” shall be same material as specified above, fabricated to required length. Consult vendors for availability.

B. Nail head covers (bibs) for slate repair work: 16 oz. or 20 oz. copper, Grade HOO (cold rolled),

complying with ASTM B370, or lead coated copper complying with ASTM B101, Type 1, Class A. Bibs shall measure 3” to 4” wide by 8” long. Snip bibs along their long sides to form barbs and/or bend to a slightly concave or S-shape prior to insertion to help prevent the bibs from sliding out. (See paragraph 3.7, below for alternate materials associated with short term repair work.)

C. Cants for starter course of slate shingles: Wood cants, standard 3/16”-1/4” thick plaster lath, tapered horse feather shims, or ripped rot-resistant lumber. Fabricate to height and width required to permit first and subsequent courses of slate to lie flat atop underlying courses.Note to Specifier: For slates greater than 1/4” in thickness, thickness of cant should match that of slate starter course.

1. Where shown in the Detail Drawings, brake inverted V-shaped cants directly into metal drip edge flashings and gutter liners located at the roof eaves. Fabricate cant to height required to permit first and subsequent courses of slate to lie flat atop underlying courses.

C. Cants for starter course of slate shingles: Cants fabricated of PVC or synthetic wood trim boards

or lattice strips. Fabricate to height and width required to permit first and subsequent courses of slate to lie flat atop underlying courses.

D. Wire used for hanging slates to avoid nailing thru underlying flashings: 99.99% pure copper wire conforming to ASTM B3, 0.051” diameter, minimum. Note to Specifier: The above wire diameter is generally acceptable for slates measuring 1/4” to 3/8” in thickness and up to 20” in length. A greater wire diameter should be specified for larger slates.

E. Sealant adhesive for use as adhesive dabs below hip and ridge slates: Exterior, non-sag, gun grade, single-component, sealant adhesive complying with ASTM C 920, Type S, Grade NS, Class 12.5, use group NT, I, M, and O, or Design Professional approved alternate sealant adhesive. Color shall be manufacturer’s standard color matching that of the slate as closely as possible.

E. Asphalt flashing cement for use as adhesive dabs below hip and ridge slates: Trowel grade cement containing non-asbestos stabilizers or fibers complying with ASTM D4586. Note to Specifier: Hip and ridge slates may be set in dabs of sealant adhesive or trowel grade asphalt flashing cement to help prevent them from separating at the apex over time. The use of adhesive/flashing cement will depend on such things as local practice, available nailing area, substrate condition, roof slope, and whether a flashing material is interwoven with the hip/ridge slates.

F. Sealant for exposed nail heads (e.g., last ridge slate to be installed): Exterior, non-sag, gun grade, single-component, urethane sealant complying with ASTM C 920, Type S, Grade NS, Class 25, use group NT, M, A and O, or Design Professional approved alternate sealant. Color shall be manufacturer’s standard color matching that of the slate as closely as possible.

G. Wood Nailers: See Section 061053.


2.5 FLASHING MATERIALS

A. See Section 076200 for flashings, gutters, and leaders (downspouts).

2.6 LIGHTNING PROTECTION MATERIALS

A. See Section 264113 for materials and fasteners to be used for securing lightning protection conductor cables and air terminals to slate shingle roofs.

2.7 SLATER'S TOOLS (p.22-25)

A. The following traditional slating tools shall be used for installation of the slate shingles:

1. Slate hammer for punching and nailing slate shingles.

2. Ripper for removing slate shingles.

3. Slate cutter or a slater’s stake and slate hammer for trimming and cutting slate shingles.

4. Steel punch or drill with masonry bit for forming holes in delicate or small pieces of slate.

B. Slates trimmed or cut on site shall have a bevel-edge similar to that produced at the quarry. Note that a grinder or saw shall not be used for cutting/trimming field slates as they will not produce a beveled edge similar to that produced at the quarry.

C. The use of nail guns for installing slate shingles shall not be permitted.

PART 3 – EXECUTION

3.1 GENERAL

A. Examine the roof deck and verify that it is satisfactory condition and ready to receive the new roof underlayment and slate shingle system.

1. Verify that the roof deck is well secured to the roof framing, free of warping or cupping, free of projecting fasteners, and the edges between boards [plywood panels] are flush.

2. Verify that the roof deck is clean, dry, and free of dew, frost, or other contaminants that might interfere with the laying or long-term durability of the slate roof system.

3. Report deficiencies in the roof deck to the Design Professional prior to commencing work.

B. Slating shall begin at the roof eave and progress toward the ridge/top of the roof slope.

C. Sorting (p.50): Sort slate shingles for thickness prior to installation on the roof. Sort shingles by hand into three [two] [four] thicknesses as follows:Note to Specifier: Sorting is generally used on uniform and random width slate roofs where a highly uniform slate roof with a very smooth appearance is desired. Sorting is not necessary where a good deal of texture, shadow lines, and uneven surfaces are desired. Sorting is also required for graduated roofs, but here it is understood that the slate will decrease in size as slating progresses from the roof eave up slope to the ridge. If a more textural appearance is desired, this paragraph may be deleted.

1. Thin: For use in slate courses closest to the ridge.


2. Thicker: For use in slate courses in “middle” courses.

3. Thickest: For use in the slate courses closest to the eave.

4. The goal is to create a roof of smooth, uniform appearance. Slate of different thicknesses shall not be used adjacent to each other.

5. To the extent possible, transitions between the different thicknesses of slate should occur at hips, ridges, vertical walls, and other non-conspicuous locations, rather than in the field of the roof, to preclude obvious discontinuities in thickness.

D. Blending (p.50): To help account for the natural variation in the coloration of the slate shingles, blend slates from several different pallets as it is brought to the roof surface to help provide for a more uniform overall appearance.

1. Blending may occur prior to, or in association with sorting.

E. Culling: No broken or cracked slate shall be used. Sound each slate for defects by tapping with a slate hammer or other metal object as it is being installed. Reject and dispose of all slates that do not emit a sharp, clear ring when tapped (p.16), or set aside for potential review by Supplier.

1. Cull and discard, or set aside for potential review by Supplier, warped and cupped slate shingles, those that are out of square, those with knots, knurls, or cramps on their unexposed faces (p.16-18), and slates with visible inclusions of iron pyrite.

2. Cull and discard, or set aside for potential review by Supplier, slates that are unusually thin or thick (i.e., slates that will be subject to breakage, cause excessive shadow lines, or cause the butt ends of overlying slates to stick up) (i.e., those outside the thickness tolerances specified in Part 2 of this Section) as well as those with curvature or twist greater than 1/8” in 12” across the width of the slate.Note to Specifier: For projects where a more textured appearance is desired, consider omitting all, or portions of, the above paragraph.

F. Nail holes made on site in slates shall be punched or drilled from the back of the slate to produce a small recess, or countersink, on the exposed face of the slate to accept the nail head.

1. Drill nail holes in slates where a nail used to secure a clip, cleat, or lock strip associated with a flashing must pass through an underlying slate. Similarly, drill nail holes in slates that taper to a point or have a small nailing area, such as hip slates.

G. Slates cut on site shall be cut from the back of the slate to maintain a beveled edge on the exposed face.

H. Slate Order: As work progresses, check that the quantity of slate remaining on site is sufficient to complete the Project. Order additional quantities of slate in a timely manner, as required, so as not to delay final completion of the project and to allow proper blending of the slate.

3.2 REMOVAL OF EXISTING SLATE SHINGLES (p.213, 220-223)

A. Slate Roof Replacement - Disposal

1. Remove all slate shingles and associated underlayments down to the roof deck. (Note to Specifier: Starting with the 2012 IBC, it is acceptable to leave existing self-adhered ice dam protection membrane underlayment in place and cover over it with another layer of ice dam protection membrane.)


a. Pull/remove (do not drive-in) all slating nails and fasteners associated with existing underlayments.

b. Deck irregularities: Identify broken, warped, cracked, rotted, or otherwise deteriorated or irregular roof decking and framing that would make the substrate unsuitable as a substrate for new underlayments and new slate roofing, and report to the Design Professional.

c. During the course of the Work, protect from damage all roofing, flashings, rainwater conduction systems, and other building and site elements scheduled to remain. Protect interior finishes and contents from moisture damage during the course of the Work.

d. Lower demolition debris to grade using enclosed chutes or other means. Plan method of removal from elevated heights. Remove in a controlled manner. Do not throw demolition debris off of the roof.

e. Clean work area and surrounding areas at grade to remove all slate chips, roofing nails, and other debris on a daily basis and at the end of project. The site shall be left clean.

f. Remove no more slate than can be reinstalled or made weathertight by the end of the day.

g. Comply with the requirements of Section 024119 – Selective Demolition.

A. Slate Roof Replacement - Salvage

1. Starting at the top of each roof slope, carefully remove all slate shingles and associated underlayments down to the roof deck and salvage slate for reinstallation [delivery to a salvage company] [palletization at grade by a salvage company]. (Note to Specifier: Starting with the 2012 IBC, it is acceptable to leave existing self-adhered ice dam protection membrane underlayment in place and cover over it with another layer of ice dam protection membrane.)a. Carefully remove existing slate shingles, one at a time, without breaking or cracking

to the maximum extent possible.b. Salvage only sound slate – slate that rings true when tapped with one’s knuckles, a

slate hammer, or other metal object, with nail holes intact, and possessing whole corners. Properly dispose of slate that cannot be salvaged.

c. Stack salvaged slate at grade, on edge, and cover to protect from the weather.d. Pull/remove (do not drive-in) all slating nails and fasteners associated with existing

underlayments. e. Deck irregularities: Identify broken, warped, cracked, rotted, or otherwise

deteriorated or irregular roof decking and framing that would make the substrate unsuitable as a substrate for new underlayments and new slate roofing, and report to the Design Professional.

f. During the course of the work, protect from damage all roofing, flashings, rainwater conduction systems, and other building and site elements scheduled to remain. Protect interior finishes and contents from moisture damage during the course of the Work.

g. Carefully lower salvaged slates to grade to limit breakage. Lower demolition debris to grade using enclosed chutes or other means. Plan method of removal from elevated heights. Remove in a controlled manner. Do not throw demolition debris off of the roof.

h. Clean work area and surrounding areas at grade to remove all slate chips, roofing nails, and other debris on a daily basis and at the end of project. The site shall be left clean.

i. Remove no more slate than can be reinstalled or made weathertight by the end of the day.

j. Comply with the requirements of Section 024119 – Selective Demolition.

B. Partial Slate Removal at Roof Eave (p.220-221)


1. Remove, salvage, and reinstall existing slate shingles at roof eave in preparation for installation of new gutters and ice dam protection membrane. (Note to Specifier: The saw-tooth method outlined below applies equally well to apron flashings at changes in roof plane, the interface of a low-slope roof with a slate roof, at large gussets or crickets, and other locations where multiple courses of slate must be removed in order to affect a repair. Modify the first sentence of subparagraph 1 as appropriate.)

2. Remove slate in a saw-tooth pattern as shown in the Detail Drawings. (Option: Reference pages 220-221 in Slate Roofs: Design and Installation Manual, 2010 Edition, or insert a detailed description of the removal process, which can also be found in the Manual.)a. Slate shall not be removed in continuous, horizontal courses, as this will require that

every slate in the top course be secured with a single fastener when reinstalled (either with a nail-and-bib or a slate hook), which will cause the slates in this course to skew over time.

b. Remove slates in accordance with subparagraph A., Slate Roof Replacement – Salvage, above.

3. Number the slates as they are removed so that they can be reinstalled in their original locations. Place the numbers on the back, unexposed, face of the slates.

4. Remove existing underlayments to expose the roof deck. Clean and inspect the roof deck for deterioration and damage. See Section 061053, Rough Carpentry, for deck repair. Install specified ice dam protection membrane. Cover ice dam protection membrane with specified roof underlayment. Extend new ice dam protection membrane and roof underlayment up-slope sufficiently so as to lap under existing roof underlayment to remain. Lap shall be 2”, minimum, unless otherwise required by Code. (Note to Specifier: Starting with the 2015 Edition, the IBC requires greater laps in areas subject to high-winds.)

4. Remove and replace damaged underlayments. Extend new roof underlayment up-slope sufficiently so as to lap under existing roof underlayment to remain. Lap shall be 2”, minimum, unless otherwise required by Code. (Note to Specifier: Starting with the 2015 Edition, the IBC requires greater laps in areas subject to high-winds.)

5. Reinstall salvaged slate shingles in accordance with Paragraph 3.4, below.

6. If slates are broken during the removal, salvage, and reinstallation process, replace the broken slates with new [reclaimed] slates as specified in Part 2 of this Section to match the original slates size, thickness, color, and texture.

C. Partial Slate Removal at Valley (p.222-223)

1. Remove, salvage, and reinstall existing slate shingles at valley in preparation for installation of new open [closed] valley flashings and new valley underlayments.

2. Remove slates from both sides of the valley in a stepped pattern as shown in the Detail Drawings. (Option: Reference pages 220-221 in Slate Roofs: Design and Installation Manual, 2010 Edition, or insert a detailed description of the removal process, which can also be found in the Manual.)a. Remove slates in accordance with subparagraph A., Slate Roof Replacement –

Salvage, above.

3. Number the slates as they are removed so that they can be reinstalled in their original locations. Place the numbers on the back, unexposed, face of the slates.


4. Remove existing underlayments to expose the roof deck. Clean and inspect the roof deck for deterioration and damage. See Section 061053, Rough Carpentry, for deck repair. Install specified ice dam protection membrane. Cover ice dam protection membrane with specified roof underlayment. Extend new ice dam protection membrane and roof underlayment up-slope sufficiently so as to lap under existing sound roof underlayment to remain. Lap shall be 2”, minimum, unless otherwise required by Code. (Note to Specifier: Starting with the 2015 Edition, the IBC requires greater laps in areas subject to high-winds.)

4. Remove and replace damaged underlayments. Extend new roof underlayment up-slope sufficiently so as to lap under existing sound roof underlayment to remain. Lap shall be 2”, minimum, unless otherwise required by Code. (Note to Specifier: Starting with the 2015 Edition, the IBC requires greater laps in areas subject to high-winds.)

5. See Paragraph 3.3, below, and the Detail Drawings for installation of new valley underlayments.

6. See Section 076200 and the Detail Drawings for installation of new open [closed] valley flashings.

7. Reinstall salvaged slate shingles in accordance with Paragraph 3.4, below.

8. If slates are broken during the removal, salvage, and reinstallation process, replace the broken slates with new [reclaimed] slates as specified in Part 2 of this Section to match the original slates size, thickness, color, and texture.

3.3 UNDERLAYMENT INSTALLATION (p.64-78)

A. Verify that the roof deck is ready to accept the roof underlayment. Notify Design Professional in writing of any unsuitable conditions, such as voids, damage, or unsupported areas.

1. Mechanical fasteners used to secure the roof decking shall be set flush with the surface of the decking and fastened into solid blocking or framing members.

2. All surfaces shall be clean, dry, and free of oil, grease, dirt, frost, dew, and other contaminants that could cause damage to the roof underlayment.

3. Decking shall be smooth, planar, continuous, and have adjacent edges set flush.

B. Ice Dam Protection Membrane: Install ice dam protection membrane at eaves, extending up slope at least 2 feet beyond interior side of exterior wall line, measured in a horizontal plane, or as indicated in the Detail Drawings. Note to Specifier: See comments regarding the retention or deletion of requirements related to ice dam protection membrane at Paragraph 2.3.B, above.

1. Install ice dam protection membrane full length of valleys and in crickets as shown in the Detail Drawings, lapping bottom end on top of ice dam protection membrane installed at the roof eave.

2. Install ice dam protection membrane stripping along the top edge of metal gutter liners and crickets as shown in the Detail Drawings.

3. At vertical walls, dormer cheek walls, party walls, chimneys, etc., extend ice dam protection membrane up the vertical surface 4 inches, minimum, or as shown in the Detail Drawings.

a. See Paragraph C., below, for flashing of pipe penetrations.


4. Prior to installation of ice dam protection membrane, vacuum roof deck to remove all dust and debris. Install ice dam protection membrane directly to the roof deck in accordance with membrane manufacturer's instructions. Lap sides 3-1/2”, minimum, in direction to shed water. Lap ends 6” minimum. Roll all laps with roller.a. Prime roof deck as recommended by the ice dam protection membrane

manufacturer if good adhesion is not obtained and when temperatures fall below 50 degrees Fahrenheit.

5. Cover ice dam protection membrane with roof underlayment as outlined below.

C. Felt UnderlaymentNote to Specifier: Although a single layer of felt (with 2”, minimum, side laps, and 6”, minimum, end laps) is acceptable in some circumstances, a double layer of felt is best practice and is what is specified below.

1. Install double layer of specified felt underlayment in horizontal courses in shingle fashion to shed water, beginning at eave line and covering entire roof area. Install an 18” wide starter course of underlayment at the roof eave and completely cover with full-width first course. Install the second course such that it laps the first course 20”. Install succeeding courses laid 17” to the weather (lapping previous courses 19”, providing for a 2” headlap). Lap ends of felt 6”, minimum. Stagger end laps of each layer a minimum of 6 feet. Secure felt along laps, ends, and in field of felt with specified fasteners as necessary to properly hold the felt in place and protect the building from water infiltration until covered with slate shingles. Fasteners placed along laps shall be spaced at no more than 36” on center.

Note to Specifier: The IBC contains a specific minimum fastening pattern for felt underlayment applied in areas subject to high wind speeds. Language consistent with Code should be inserted in lieu of the above if the project is located in an area of high wind. See, for example, Section 1507.7.3.1 of the 2015 IBC and Table 1507.1.1(3) of the 2018 IBC,

2. Felt shall lap hips and ridges 12” to form double thickness.

3. At vertical walls, extend felt underlayment up the vertical surface 4” minimum, unless otherwise shown in the Detail Drawings.

4. Flash penetrations through the roof using specified ice dam protection membrane to provide for a secure and watertight assembly. Ensure ice dam protection membrane target flashing is large enough to permit top edge of metal flashing to be installed to be stripped-in with ice dam protection membrane (i.e., stripping to be centered on top edge of metal flashing and be installed directly to the metal flashing and directly to previously installed ice dam protection membrane).

5. At roof eaves, the first layer of felt underlayment shall lap below the metal drip edge and the second layer of felt shall lap on top of the metal drip edge. At rakes, both layers of felt underlayment shall extend below metal drip edge.

6. Cover roof underlayment with slate shingles as soon as possible. Remove and replace felts that have become wrinkled or damaged, or that have been exposed on the roof for more than 30 days. Maximum length of exposure for felts shall be 30 days.

C. Synthetic Underlayment

1. Install specified synthetic roof underlayment in accordance with manufacturer’s instructions.

a. Comply with manufacturer’s requirements regarding placement of underlayment over, or under, metal drip edge flashings at eaves and rakes.

b. Comply with manufacturer’s requirements regarding horizontal and end laps.


c. Comply with manufacturer’s minimum ambient temperature requirements for installation.

Note to Specifier: The IBC contains a specific minimum fastening pattern for underlayment applied in areas subject to high wind speeds. Language consistent with Code should be inserted in lieu of the above if the project is located in an area of high wind. See, for example, Section 1507.7.3.1 of the 2015 IBC and Table 1507.1.1(3) of the 2018 IBC,

2. If exposed cap-nail installation method is used, all cap nails must be covered with specified single-sided tape. If concealed cap-nail installation method is used, all seams must be adhered using specified double-sided tape or adhesive sealant. a. Install cap nails at spacing and in pattern specified by manufacturer. b. Cover any punctures caused by fasteners associated with temporary strapping or

staging with specified single-sided tape.c. Turn roof underlayment up at vertical walls a minimum of 4”, unless otherwise

shown in the Detail Drawings.

3. Flash penetrations through the roof using specified single-sided tape and/or manufacturer’s self-adhering membrane to provide for a secure and watertight assembly.

4. Cover roof underlayment with slate shingles as soon as possible, and in all cases within manufacturer’s maximum exposure window for the underlayment. a. Limit foot traffic on this underlayment. Do not scuff the underlayment.

D. Replace damaged roof underlayments immediately. Do not install slate shingles over damaged underlayment.

E. Upon completion roof underlayment shall be smooth and free of punctures, holes, gashes, wrinkles, deep scuffs, and other defects that could compromise the underlayment’s ability to serve as a temporary roof and secondary water shedding membrane.

3.4 SLATE INSTALLATION

A. Protection of Roof Surfaces

1. The roof is to be properly staged to allow safe work surfaces, such as brackets and planks, that prevent unnecessary foot traffic on the slates.

2. Where foot traffic is unavoidable, roof ladders, hook ladders, chicken ladders, foam pads, or other such devices shall be used to protect the slates.

3. Workers are to avoid walking on the slate surfaces during, and after, installation.

B. Laying Out the Roof (p.56-60)

1. Check that the eave is straight and level, the ridge is parallel to the eave, and that the gable ends are square with the eave. Note to Specifier: For unusually shaped roofs, specify the establishment of a horizontal line for the slate courses. Note too, that in some instances slate shingles are not laid in horizontal courses, but rather are laid in a wave, crisscross, or some other pattern.

2. Snap a line for locating the starter course equal to the vertical dimension of the starter slate minus the specified overhang (1½”, or as otherwise shown on Detail Drawings). Set the starter course parallel to the eave. If the eave is not straight, make small adjustments in successive courses until the course lines are straight and parallel.


3. Chalk the line for the first course by measuring up from the eave the length of the slate, minus the specified overhang.

4. Chalk the line for the last full course at the ridge (finishing course), making sure it has an exposure of __”, or as shown in the Detail Drawings. Adjust the exposure of the courses approaching the ridge in small increments to obtain the required exposure of the finishing course (see subparagraph 5). Note to Specifier: The exposure of the finishing course should never be greater than the exposure of the field slates as this can result in inadequate headlap.

Note to Specifier: From an aesthetic point of view, for the exposure of the finishing course to look right, it should not be too short or too long. In general, the exposure of the finishing course should be equal to the exposure of the field slate, or slightly less. As such, the exposure of the finishing course in subparagraph 4, above, can be filled-in with a fixed dimension or a range of dimensions. If a fixed dimension, consider specifying the field exposure, or a dimension one to two inches less than the field exposure (e.g., 6-1/2” on a roof requiring a 3” headlap and laid with 18” long slates). If a range of dimensions (i.e. a fixed exposure of from __” minimum, to ___”, maximum) consider basing the minimum dimension on aesthetics (generally no less than about 2-1/2”) and the maximum dimension as discussed above for the fixed dimension; an exposure of 4” (min.) to 7” (max.), for example, on a roof requiring a 3” headlap and laid with 18” long slates. Note that, in some instances (e.g., staggered butt or drop down), slate shingles have varied exposures and this will have to be taken into consideration when specifying the exposure of the finishing course of slate. See also pages 162 (Note 14.D) and 166 of Slate Roofs: Design and Installation Manual, 2010 Edition.

5. Snap horizontal lines based on the exposure of the slate, making small adjustments as needed so the courses end up parallel to the ridge and the exposure remains within ¼” of adjacent courses. When within 5 to 10 feet of the top of the slope, re-measure, and adjust the exposure in the remaining courses in small increments (1/8” to 1/4” per course) as needed for proper coursing. Do not reduce the headlap; always decrease the exposure so as to increase the headlap. (This same procedure applies to the laying out of courses at the bottom and top of dormers to assure that the courses line up.) (Note to Specifier: The goal is to control the exposure of the finishing course such that it is slightly less than or equal to the exposure of the field slates. Very small and very large exposures at the finishing course are not aesthetically pleasing. See also Note 14.D on page 162 of Slate Roofs: Design and Installation Manual, 2010 Edition.)

Note to Specifier: Should there be a bow in the ridge, there are generally three ways in which to address this condition. The first transitions from horizontal coursing, laid parallel to the roof eave, to coursing that is parallel to the ridge. The second maintains horizontal coursing and accounts for variations in the ridge by trimming the finishing course slates to length. The third method combines the first and second methods outlined above. Which method is used depends on the degree of bow and the finished aesthetic desired by the Owner. For example, the second method (addressing the bow in the finishing course) is generally appropriate if the ridge is out of true by 1” or less. Whichever method is used, the reconciliation should take place within an appropriate number of courses of the ridge to accommodate the deviation from true. Consider adding a test panel to Paragraph 1.6, above, to address the issue and receive Owner approval.

6. When laying out a roof with uniform width slates, snap two vertical lines near the center of the roof to establish the slate’s bond lines. The space between the two vertical lines should be equal to one-half the width of the slate. (p.59, Figure 2.28)


7. If the eave and/or ridge are not horizontal, establish a level line as a reference for snapping the course lines. Slate courses shall run horizontally. Treatment of special conditions shall be incorporated in the Test Panels under Paragraph 1.6, above.

C. Eave (p.70-75)

1. The starter course of slates shall be laid horizontally (with the long edge parallel to the roof eave) with the bevel-edged side facing down, and be canted to allow the starter slates to be tilted to the same angle as the field slates.

2. The starter slates shall have nail-holes 1” to 1½” down from the top, long edge of the slate, and approximately 1½” in from each short edge.

3. Eave slates shall be laid to provide the specified overhang (1½”) [1¼”] [1”], or as shown in Detail Drawings) beyond the furthest extent of the fascia, cornice, crown molding, metal drip edge, trim, or other construction material at the eaves.

4. Slates at the eaves shall be doubled by first installing a slate starter course. The first course of slate shall be laid over the starter course so that the butt edges of both courses align. The first course of slate shall break side joints with the starter course side joints by not less than 3”. The second course of slates must overlap the starter course by at least the headlap of the field slates along the eaves.

D. Gable Ends (p.79-82)

1. Rake edge (gable end) slates shall extend approximately 1” beyond the gable trim, fascia, or drip edge.

2. Adjust the width of field slate as needed to avoid gable end slate of less than 6” width. (Note to Specifier: For a discussion of approach slates, see page 79 of Slate Roofs: Design and Installation Manual, 2010 Edition.)

E. Field Slates (p.40-41 and 83-87)

1. Exposure and Headlap a. All standard field slates shall be installed with a minimum 3" headlap when the roof

slope is 8:12 up to 20:12.a. All standard field slates shall be installed with a minimum 4" headlap when the roof

slope is 4:12 up to 8:12. a. All standard field slates shall be installed with a minimum 2" headlap when the roof

slope is greater than 20:12.b. Headlap shall be increased to __” at ice-dam prone or poor-drainage areas. (Note

to Specifier: Some designers will increase the headlap in order to mitigate the likelihood of water making its way below the slate shingles. Note, longer slates may need to be specified in order to maintain exposure.)

2. Offset: Slate side joints shall be positioned as near the mid-point of the underlying slates as possible, and not less than 3" from the underlying joints. Note to Specifier: 3” offset is standard for roof slopes 8:12 and above. For roof slopes less than 8:12, consider increasing the offset to 3-1/2”, 4”, or more, and increasing the length and width of the slate specified in Part 2, above, in order to better accommodate lateral water migration below the slates and help prevent that water from reaching the nail holes in the course below. For example, on a uniform roof with a 6:12 slope, one might specify 20x12 slates in preference to 18x10s and increase the minimum offset to 4”.


3. Joint Spacing: Slates shall be laid nearly touching side-to-side, or with a gap of approximately 1/16” [1/8”] [1/4”] [3/8”] [1/2”] between slates (see Manual p.83, Note 3, and NSA Technical Bulletin #2). Small adjustments can be made in joint spacing and/or slate width as needed when approaching rakes or walls to avoid use of excessively narrow slates; no slate shall measure less than 6” in width.

4. Fastening – Nailing and Wiring (p.51-52)a. Secure each slate to the roof deck with two nails set in holes pre-punched or drilled

at the quarry, or punched by hand on site.b. Slates measuring ¾” or more in thickness and 20-inches or more in length, shall be

secured with four nails each. Place the two additional nails approximately 2” above the regular nail holes.

c. Set each nail with the head set in the countersink left by the punching of the nail hole; nails must not be over-driven, nor under-driven; nail heads shall touch the slate lightly, without producing strain on the slate and such that the slates hang from the nails.

d. Slates located adjacent to flashings shall be nailed to avoid puncturing the flashing material. Move one or both of the nails up, or closer to the center of the slate; secure the slate with a second nail placed one above the other on one side of the slate; or, secure the slate with copper wire fastened to the roof deck upslope of the top edge of the flashing.

5. Shapes: The slate shape shall be rectangular [gothic] [clipped corner] [hexagon] [fish scale] [diamond]. (Note to Specifier: The standard shape for natural roofing slate is a rectangle with the long dimension laid parallel to the roof slope. Slate shingles can also be supplied in special shapes with the exposed butt trimmed If special shapes are specified, provide trimming dimensions and/or Detail Drawings. See Slate Roofs: Design and Installation Manual, 2010 Edition, p.10-11.)

Note to Specifier: For all slate shapes, ensure that all slate to be used on the roof are either all Imperial (inch) sizes or all Metric (centimeter) sizes so that joint spacing can be maintained throughout the roof. See also Paragraph 2.1.D, above.

6. Banding, Color Bands, and Decorative Patterns: (Note to Specifier: Patterns can be introduced with slates of different colors and/or shapes. The designer should provide Detail Drawings showing the desired layout for colors and shapes.)

Note to Specifier: For all patterns, ensure that all slate to be used on the roof are either all Imperial (inch) sizes or all Metric (centimeter) sizes so that joint spacing can be maintained throughout the roof. See also Paragraph 2.1.D, above.

F. Valleys (p.97-107)

1. Valleys shall be open [closed] [round] [swept] [canoe]. a. Open Valleys

i. Slates at the edges of valleys shall be cut in neat and straight lines. Ii. Valley slates are to be cut from the back of the slate to maintain a beveled

slate edge.iii. Clip the upper corner of valley slates to allow the slate to lay correctly and to

direct moisture toward the valley centerline.iv. For fabrication of valley flashing, see section 076200.v. Lay slate a minimum of 3”-4” each side of the valley centerline. Taper

outward 1/16” per foot from top to bottom to allow for release of ice.vi. When fastening slates, do not puncture valley flashing with nails. Use wider

slates as needed; place two nails, one above the other along the edge of the


slate farthest from the valley centerline; or, hang slates from copper wire secured above the top edge of the valley flashing.

vii. Adjust width of slates approaching a valley to avoid the need to cut slate to a point at the valley; width of the butt of the valley slate shall be 3” minimum.

b. Closed Valleysi. Slates at the edges of valleys shall be cut in neat and straight lines. ii. Valley slates are to be cut from the back of the slate to maintain an exposed

beveled slate edge.iii. Clip the upper corner of valley slates to allow the slate to lay correctly and to

direct moisture toward the valley centerline.iv. For fabrication of valley flashing, see section 076200.v. Interweave closed valley flashing with each course of slate as the slates are

being installed.vi. Extend valley flashing 2”, minimum, beyond top edge of the slate and fasten

to the deck without penetrating the slates.vii. Each flashing shall be set back from the butt of the slate above by no more

than ½” so that it will not be visible.viii. When fastening slates, do not puncture valley flashing with nails. Use wider

slates as needed; place two nails, one above the other along the edge of the slate farthest from the valley centerline; or, hang slates from copper wire secured above the top edge of the valley flashing.

ix. Adjust width of slates approaching a valley to avoid the need to cut slate to a point at the valley; width of the butt of the valley slate shall be 3” minimum.

x. Align the butt ends of the slates in each course on either side of the valley.Note to Specifier: For round, swept, and canoe valleys, see Slate Roofs: Design and Installation Manual, 2010 Edition, p.103-107.

G. Penetrations (p.182-191)

1. Slate shall be neatly fitted around pipes, ventilators, and other roof penetrations.a. Do not nail through flashings.b. Trim slates neatly.c. See Section 076200 for flashings.

H. Flashings

1. Integrate flashings as slates are being installed.a. See section 076200, Sheet Metal Flashing and Trim. b. Flashing shall be installed where there are roof plane intersections, where the roof

abuts walls, parapets, dormers and chimneys, at roof penetrations, and where shown on the Drawings.

c. See Slate Roofs: Design and Installation Manual, 2010 Edition for typical flashing installations not shown in the Detail Drawings.

I. Hip and Ridge Slates: See Paragraphs 3.5 and 3.6, below.

J. Slate Repair

1. Where individual slates must be installed in the field of the roof after the installation is complete, such as where a roof bracket has been removed or where a broken slate must be removed and replaced, such installation shall be made in accordance with the slate repair procedures specified in Paragraph 3.7, below.

K. Coordinate slate installation with the installation of snow retention devices specified in Section 077253.


3.5 RIDGE SLATES (p.158-181)Note to Specifier: There are several different ridge types that may be specified and it is best to provide a detail drawing showing project specific requirements. If a continuous metal ridge flashing is to be installed, a strip saddle ridge should be specified in this Section. The information below should be amended and supplemented as required.

A. Install ridge slates (finishing course slates) in a saddle ridge [strip saddle ridge] [comb ridge] [projecting saddle ridge] [ventilated ridge] pattern, laid horizontally [vertically], as shown in the Detail Drawings and in accordance with approved test panels. Coordinate with installation of new copper ridge flashings (see Section 076200) (applicable only to saddle and ventilated ridges and ridges scheduled to receive continuous metal ridge flashing) and associated wood blocking.

1. Ensure roof underlayment is whole and overlaps the ridge a minimum of 12” in each direction.

B. Secure each ridge slate with 3 nails set approximately 1-1/2 inches down from the top edge of the slate [3 or 4 nails arranged in a triangular or diamond pattern]. In addition, set the bottom edge of each slate in dabs of specified adhesive [flashing cement].

1. Nails holes in ridge slates may be drilled, instead of punched, in order to limit breakage and loss of section around the nail holes. Nail holes through underlying slate shingles shall be drilled, not punched.

C. Snap chalk lines to provide straight ridge lines. Accommodate lack of trueness in structural framing of ridges by selectively trimming slates or using slightly wider slates in localized areas as required to produce a line that is straight.

D. Lay ridge slates so as to accommodate the prevailing wind direction. (Not applicable to strip saddle ridges.)

3.6 HIP SLATES (p.142-157)Note to Specifier: There are several different hip types that may be specified and it is best to provide a detail drawing showing project specific requirements. If a continuous metal hip flashing is to be installed, a mitered hip (without interwoven flashings) should be specified in this Section. The information below should be amended and supplemented as required. If the ridge type and hip type are similar (e.g., saddle ridge and saddle hip), Paragraphs 3.5 and 3.6 may be combined.

A. Install hip slates in a saddle hip [mitered hip] [Boston hip] [fantail hip] [projecting saddle hip] pattern, as shown in the Detail Drawings and in accordance with approved test panels. Coordinate with installation of new copper hip flashings (see Section 076200) (not applicable to projecting saddle hip) and associated wood blocking.

1. Ensure roof underlayment is whole and overlaps the hip a minimum of 6” to 12” in each direction.

B. Secure each hip slate with 3 or 4 nails arranged in a triangular or diamond pattern. In addition, set the bottom edge of each slate in dabs of specified adhesive [flashing cement].

1. Nails holes in hip slates may be drilled, instead of punched, in order to limit breakage and loss of section around the nail holes. Nail holes through underlying slate shingles shall be drilled, not punched.

C. Snap chalk lines to provide straight hip lines. Accommodate lack of trueness in structural framing of hips by selectively trimming slates or using slightly wider slates in localized areas as required to produce a line that is straight.


3.7 SLATE SHINGLE REPAIR (p.213-219)

A. Replacement slates shall match the existing in type (region where quarried), color, weathering characteristics, size and thickness (or slightly thinner), shape, and texture - see Part 2, above. Note to Specifier: Reclaimed slates may be used to provide a match for an aging roof, if they are of equal quality/remaining service life to the existing. If reclaimed slate is desired for slate repair work, the material should be specified in Part 2 of this Section (see Paragraph 2.1.A, above).

B. Where existing slates are to be removed, salvaged, and reinstalled in conjunction with flashing repair and/or replacement work number the slates on their back sides such that they can be reinstalled in their original locations.

C. Remove existing broken slates and associated slating nails using a slate ripper. If the head of a slate cannot be removed in this manner, carefully remove adjacent slates as required to provide a fragment-free and clear space for the replacement slate.

D. Replacement slates shall be fastened using one of the following methods:

1. Nail-and-Bib Method: a. Slide replacement slate into position.b. Punch or drill a nail-hole through the replacement slate about 1” below the butt of the slate

two courses above. Locate this nail-hole in the bond line between the slates in the course immediately above.

c. Fasten the slate with a single copper slating nail placed in the nail hole. d. Insert a copper sheet-metal bib under the course above to cover the head of the nail. Push

the bib past the butt end of the slates in the course above such that the bottom edge of the bib is no longer exposed and the bib provides for the same headlap as the slate. Pre-bend and/or notch the edges of the bib to prevent it from sliding out.

Note to Specifier: For temporary or short-term repair work (e.g., on a roof with a limited remaining service life), alternate materials may be used in lieu of copper. These include aluminum bibs and either electroplated or hot-dipped galvanized steel nails. e. For slates measuring ¾” thick and 20” long (or larger), use two nails, with the second nail

placed about 1” below the first.

2. Slate Hook Method: a. Install the slate hook prior to sliding the replacement slate into position. b. Drive the slate hook into the roof deck through the joint between the slates in the course

below with the hook aligned with the desired position of the butt of the replacement slate. c. Slide the replacement slate up into position, past the hook, and then pull it back down to

engage the butt end in the hook.d. Do not use slate hooks when replacing multiple adjacent slates in the same course. e. Do not use slate hooks for slates thicker than 3/4”. f. Do not use standard slate hooks when the headlap is greater than 3” – custom slate hooks

must be fabricated (see Part 2 of this Section).

3.8 SNOW GUARDS AND SNOW RAILS (p.239-240)Note to Specifier: Some specifiers prefer to include the specification of snow retention systems in the Slate Shingles specification section, especially if snow guards and/or snow rails are to be installed on an existing slate roof as this will usually entail the removal, salvage, and reinstallation of slate shingles.

A. See Section 077253, Snow Guards, for new snow retention systems.

B. Coordinate installation of new snow retention systems with installation of slate shingles.

1. See Roof Plan for required locations for new snow retention devices.


Note to Specifier: If adding a snow retention system to an existing roof that never had snow retention devices, it may be prudent to have a licensed structural engineer verify that the roof framing can accommodate any additional loads that may be imposed. Note that the Ground Snow Load will not change by virtue of the fact snow retention devices are being added, but whereas previously snow would typically slide off the roof, it will now be retained on the roof and the possibility of accumulating drifting snow now exists (especially with the use of snow rails). Adding 3 rows of snow guards or a short length of snow rail in a localized area, such as above an entrance typically will not be a cause for concern. Installing a snow rail near the eave and additional snow rails or snow guards further upslope, over an entire roof area, on the other hand, is much more significant and should initiate the call for a structural analysis. Note too, that a change in use of the building or structure could change the load requirements of the structural system and mandate that an analysis of snow loads be undertaken.

Note to Specifier: If replacing an existing roof that contains snow guards and/or snow rails and the system is performing well, the existing layout can generally be incorporated into the new roof. Conversely, when introducing snow retention devices on a roof that never had them, it is prudent to consult with the manufacturer of the snow guards/rails to be specified with regard to an appropriate layout.

3.9 LIGHTNING PROTECTION SYSTEMS

A. See Section 264113, Lightning Protection for Structures, for new lightning protection system requirements.

B. Coordinate installation of new lightning protection system with installation of slate shingles.

1. Do not permit lightning protection system components to be secured with fasteners set directly through slate shingles or associated flashings.

2. See Section 264113 for fasteners to be used to secure lightning protection system components in the field of the slate roof. These hook on to the nails used to secure the slate shingles and may [shall] be installed by the slate roof installer. The lightning protection installer must be on site to supervise the work.

3. Discuss all lightning protection items to be secured to the roof, flashings, and gutters with the Design Professional prior to commencing work.

3.10 CLEAN-UP AND ADJUSTMENT

A. Work areas shall be left neat and clean at the end of each work day.

B. Remove debris from gutters and downspouts (if any) at the end of each work day and upon completion of the work to ensure unrestricted flow of water from the roof.

C. Upon completion of work, remove all roofing equipment, excess material, and debris from all roof surfaces and grounds.

D. While removing equipment, material, and debris from roof surfaces, inspect all work to ensure completeness, aesthetics, and undamaged workmanship. Broom clean slate shingles as roof jacks and planks (or other means of access) are being removed from the roof.

E. Dispose of debris in accordance with all local, state, and federal regulations or in the manner as stated elsewhere in the Contract Documents.


F. Remedy any incomplete work and replace any damaged, broken, poorly lying, or otherwise offending roofing slates using the repair methods specified in Paragraph 3.7, above.

G. Upon completion of clean up and adjustments, advise the Design Professional that the work is ready for final inspection and punch listing by the Design Professional.

END OF SECTION 073126
