090428 Presentation Handouteoplugin.commpartners.com/ASC/090428/090428 Presentation Handout.pdf• Compatible one to the other Photos Courtesy SmithGroup Role of SSG Material Suppliers

SSG

Fundamentals of Structural Sealant Glazing

Photos Courtesy of SmithGroup

Introduction

• This presentation is about the use of silicone sealants for structural sealant glazing (SSG)

• Information on sealants for weatherproofing applications is described in a separate presentation

• This presentation is general in nature– For in-depth information on SSG

refer to ASTM International publication “C1401 Guide for Structural Sealant Glazing”

What SSG is ― and is Not

• It is:– Adhering glass and panels to a metal

framing system• Using a structural quality silicone sealant

– Typically two- and four-side adhesion for rectilinear panels

• Other shapes – round, polygonal, triangular, etc.

• It is not:– Mechanical attachment of glass and

panels to a metal framing system– Butt glazing:

• Has no vertical mullions and is not SSG

Mechanically Attached Curtain Wall

Photo courtesy Momentive Performance Materials

SSG and Conventional Mullions

Typical Roles of Participants

• Architect– Building and SSG system aesthetic

design concept

• SSG Consultant– System technical design expertise

– Can assist throughout the project

• SSG System Fabricator– Develops a quality control system

– Designs and fabricates system

– Keeps quality control information

• SSG System Installer– Develops a quality control system

– Installs system

– Keeps quality control information

Photo Courtesy of Dow Corning

Typical Applications

• Glazing glass into windows, curtain walls, and skylights– Insulating and laminated insulating glass

(IG), monolithic and laminated glass, spandrel glass, specialty glass, etc.

• Sloped glazing and skylights– Laminated IG units typically

• Glazing other materials onto metal framing systems– Stone and stone clad composite panels– Metal panels

• Coated Metal, Aluminum, Stainless Steel, etc.

– Other miscellaneous applications


Photo Courtesy SmithGroup

SSG System Potential Risk

• Fundamentally SSG relies on:– Structural sealant adhesion no mechanical

fasteners– A typical adhesion “chain”

• Glass to structural sealant

• Structural sealant to aluminum finish

• Aluminum finish to aluminum

• Design, fabrication, and installation requires:– More technical knowledge and workmanship

skill

• Has more inherent risk– Pay attention to the details – A quality control program is required

Illustration Courtesy of Dow Corning

History of SSG Systems Development

• 1965 PPG TVS all glass system– Monolithic glass mullions

• 1970: Two-side SSG with monolithic glass

• 1971: Multi-story four-side SSG with monolithic glass

– Smith Hinchman and Grylls Headquarters building, Detroit, MI

• 1976: Two-side SSG with insulating glass• 1978: Four-side SSG with insulating glass

• 1980’s: Attachment of panels other than glass

– For example: metal, stone, and composite panels

Photos Courtesy of SmithGroup

Smith Hinchman and Grylls Building

How Durable Are SSG Systems?

• No capability to predict SSG service life– 50+ year history of successful installations.

– There have been material and workmanship problems

• Attaining and maintaining adhesion– Fundamental for success and longevity

• Use proven materials and techniques– Require prefabrication adhesion and

compatibility testing

• Must have a quality control program.– From predesign to installation

• Architect, Consultant, Fabricator, and Installer

– Inspection and maintenance• Performed periodically

Mullion Glass

Structural

Silicone

Spacer


Weather Seal

Structural Sealant Definitions

• Bite– The effective “structural” contact

dimension of a structural sealant (ASTM C717)

• Sometimes referred to as “Glueline”

• Thickness– The minimum structural sealant

dimension between structurally bonded surfaces. (ASTM C717)

• Dead load– A panel’s weight that can create

shearing stress on an SSG joint

Illustrations Courtesy of Dow Corning

Dead load Shearing Stress

Bite

Thickness “Glue line”

Structural Sealant

Spacer

Architectural Design Questions

• Will the SSG system be standard or custom?

• Will it have two- or four-side adhesion?– Four-side SSG typically factory glazed

– Two-side SSG typically site glazed

• Is an SSG consultant required?– Standard or custom system?

– Will it be a unique or ground breaking system?

– What is its complexity, size, and potential liability?

• Is there “buy-in” for the system from all stakeholders?

– Architect, Building Owner, Contractors, Code Authority, etc.

pressure plate pressure plate (mechanical (mechanical

fixation)fixation)

gasketgasket

structural structural silicone at silicone at verticalsverticals

Two-side SSG System

Four-side SSG System

Photos courtesy Momentive Performance Materials

SSG System Design Issues

• Coordinate structural sealant(s) selection– Fabrication structural sealant

• Multicomponent or single-component sealant

– Remedial work structural sealant• Single-component sealant

• SSG joint characteristics– Structural “bite” a minimum of ¼-inch.– “Glueline” thickness a minimum of ¼-inch.– Bite to thickness ratio should fall between

1:1 and 3:1.

• Install structural sealant using standard application procedures.

– Adequate installation access required


Structural Glazing Sealants

• Multicomponent– Requires mixing of two components

– Cures by chemical reaction between components

– Factory installed

– Fast cure rate, which is adjustable

• Single-Component– One-part material, no mixing

– Cures by chemical reaction with atmospheric moisture

– Factory or construction site installation

– Full cure can take as long as 2 to 3 weeks• Dependent on relative humidity level• SSG joint access to humidity

Humidity Access


Photo courtesy Momentive Performance Materials

Other Sealants

• Metal framing system sealants– Compatible with structural and

weatherproofing sealants

• Weatherproofing sealants– Use silicone sealants

• Meet ASTM C920 with Joint design by ASTM C1193 and C1472

• Single-component

• Will require adhesion testing

• Other wall system(s) sealants– Abutting systems

• Use silicone sealants, discourage use of other polymer types

• Must adhere one to the other

• Compatible one to the other

Photos Courtesy SmithGroup

Role of SSG Material Suppliers

• Sealant, glass and other manufacturers technical staff– Provide design and installation information– Require correct use of their products, such

as:• Adhesion and compatibility testing

• Cleaning, priming and sealant application

– Assist with development of system details• SSG Sealant reviews can include:

– Appropriate sealant stress level

– Proper joint configuration

• Glazing reviews can include:

– Proper drainage of IG unit glazing pocket

– Proper support of glazing


Specifying SSG Systems — Basic System Criteria

• Establish appropriate criteria– Properly specify various components– Require submission of a quality control

program

• Questions to answer:– How will maintenance access be provided?– How will maintenance activities be

accommodated?• Window washing

• Broken or failed component replacement

• Scaffolding tie-backs or tracks?

– Is attic stock needed?• Which items? Quantity? Where stored?

• Complicated design – more attic stock

Specifying SSG Systems — Basic Performance Criteria

• Specify appropriate testing for:– Air Infiltration ― ASTM E283– Water Infiltration ― ASTM E330– Structural ― ASTM E331,

AAMA 501.1– Sound Control– Thermal Properties

• R-Value, SHGC, Condensation resistance

– Day lighting• Visible light to solar heat gain

(LSG)– (Visible Light)/SHGC– Greater than 1

Specifying SSG Systems — Structural Joint Criteria

• Structural sealant– Meet ASTM Specification C1184

• Structural sealant design issues– 20 PSI max. structural sealant stress

– 2.5 min. structural sealant design factor

• Structural loads– Wind, dead, snow, live, seismic

• Movements– Building motion, differential thermal, live load,

dead load

• Framing effects– Elastic frame deformation, creep, shrinkage,

seismic

• Force protection– Blast and missile impact resistance

Specifying SSG Systems — Adhesion Testing

• Substrate sealant adhesion testing– Do not rely on previous test data from

another project• Changes can occur in formulation and

manufacturing process

• Require adhesion testing for every project

– Test substrates manufactured for the project - not “off the shelf”samples

• When to perform adhesion testing– During design

• Verification of new materials

– Preconstruction verification of adhesion

• For production run materials

– Periodic testing during fabrication or installation

• To monitor for any detrimental changesGranite

Painted Finishes

Anodized aluminum

Structural Sealant Adhesion Test

• Performed by SSG sealant manufacturer – Test performed using ASTM C794– Typical substrates:

• Glass (uncoated usually not tested)

– Coated glass may require deletion of coating

• Metals such as anodized, stainless steel, etc.

• Factory coated metals - adhesion can vary

– By coating type, color, and manufacturer

• Stone – usually granite

– Inherently a variable material

– Criteria for rejection• Loss of adhesion - must fail cohesively

Adhesion In-Peel Test Samples


Specifying SSG Systems — Compatibility Testing

• Component compatibility testing– System components must be

compatible• Test it if touches or is in close

proximity to a structural sealant

• No detrimental interaction required

• Typical materials:– Glazing gaskets for two-side SSG systems

– Structural sealant spacers

– Glass or panel setting blocks

– Weep system drainage tubes

– Joint fillers “back-up rod”

– Other miscellaneous organic materials

Illustration Courtesy of Tremco

Structural Sealant Compatibility Test

• Performed by SSG sealant manufacturer– Test performed using ASTM C1087

• Ultraviolet and heat exposure for 21 days

• Criteria for rejection of component– Color change of structural sealant

• Could indicate future loss of adhesion

• Sealant manufacturer evaluation

– Loss of adhesion of structural sealant• Automatic rejection Compatibility Test Samples


Specifying SSG Systems — Quality Control

• Quality control document required– Material quality verification

• Sealants, solvents, primers, and other components

– Fabrication monitoring, for example• Frame fabrication milestones

• Substrate cleaning procedures

• Substrate priming

• Two-part sealant mixing ratio and cure rate

– Installation requirements• Factory or construction site glazing?

• Panelized or stick-built system?

Photos Courtesy of Dow Corning

Specifying SSG Systems — Visual Mock-Ups

• Predesign visual mock-up(s)– Usually small scale samples– Evaluate:

• Different finishes and glass types

• Does it achieve the aesthetic goals?

• Prefabrication visual mock-up(s)– Usually large scale– Evaluate finishes and glass types

• Does it achieve the aesthetic goals?

• Can be performed at the factory or construction site

• The sooner the better


Visual Mock-Up at the Construction Site

Specifying SSG Systems — Technical Laboratory Mock-ups

• Laboratory mock-up(s) of system – Verify aesthetic intent– Verify fit of materials and components– Fine tune and debug assembly

techniques– Verify replacement and repair

techniques.

• Conduct performance tests– Air, water, structural, movements,

thermal, sound, etc.– Using industry standard test methods

• ASTM, AAMA, etc.

• Best opportunity to correct problemsFull-Scale Curtain Wall Mock-ups


Specifying SSG Systems — Technical On-Site Mock-ups

• Construction Site Mock-Up(s)– Can be used as a quality reference

during system installation

• Verify workmanship• Verify performance

– Typically air and water infiltration tests

• Disposed of when construction completed– Or can be come permanent part of

construction

• Not the best opportunity to correct problems


ASTM E330 Water Infiltration Test

Specifying SSG Systems — Construction Workmanship Testing

• Verification of workmanship– Periodically during installation– Typically for:

• Air infiltration - ASTM E783

• Water infiltration - AAMA 501.2

• Or ASTM E1105

– How many tests?• One test for every 5,000 SF? More?

Less?

• Base on project size and complexity

• Multiple systems = multiple tests

– How often to test?• Initial installation then randomly and

periodicallyAAMA 501.2 Water Infiltration Testing


The SSG Construction Process — Typical Stages

• Submittals and shop drawings• Material verification and approval

• System detail review

• Fabrication monitoring• Quality control program

– Material and component testing

• Installation monitoring• Quality control program

– Material and component testing


The SSG Construction Process — Submittals and Shop Drawings

• Review of SSG quality control program– Are all material quality, fabrication, and

erection aspects adequately described?

• Has test data for components been submitted before fabrication?

– Structural sealant(s) for adhesion– Gaskets, spacers, setting blocks, etc. for

compatibility

• Last chance for SSG system drawing detail review

• This is not the time to consider material or other substitutions


The Construction Process — Fabrication Monitoring

• Monitor quality of components– Sealants, glass, primers, gaskets, spacers,

etc.

– Periodic quality testing

– Metal framing joints, seals, and tolerances

• Document with check lists

– Structural sealant

• Cleaning, priming, and application

• Curing time before frame movement

• Milestone testing– Periodically test a completed frame

• Typically for simulated wind load


The Construction Process — Installation Monitoring

• Monitor quality of components– Sealants, primers, gaskets, spacers,

cleaners, etc.

• Periodic quality testing

– Metal framing joints, seals, and tolerances

• Documented with check lists

– Structural sealant

• Cleaning, priming, and application

• Curing time before frame movement

• Workmanship testing– ASTM and AAMA test methods

– Initially and periodically


Panelized Curtain Wall

Stick Built Curtain Wall

SSG Systems Maintenance — Post Construction

• Plan for during system design– Not later!– Capable of being economically

maintained

• Why?– Replacement of failed or broken

components– Weather sealant replacement– Periodic cleaning– Periodic inspections

• Local law requirement – usually at 5 year intervals

• Verify system continuing performance


Remedial Work — Considerations

• Plan for during system design– Not later!

• System design must permit easy access– Failed IG unit replacement

• They have a life time, replacement must be anticipated

– Broken glass replacement– Replace SSG sealant or other

components

• Attic stock facilitates rapid replacement– Especially if heat treated glass is

required

Photos courtesy Momentive Performance Materials

General Sealant Resources

www.adhesives.org

• Web site includes fundamental information on sealant chemistries, application equipment, and ASTM standards

• Features Sealant TechSelect Tool with links to vendors and contacts

www.adhesives.org/TechnologySelector.aspx

SSG Resources — Industry Standards

• ASTM (www.astm.org)– C717 Standard Terminology for Building Seals and Sealants

– C794 Standard test Method for Adhesion-in-Peel of Elastomeric Joint Sealants

– C920 Standard Specification for Elastomeric Joint Sealants

– C1087 Standard Test Method for Determining Compatibility of liquid-Applied Sealants with Accessories Used in Structural Glazing Systems

– C1184 Standard Specification for Structural Silicone Sealants

– C1193 Standard Guide for Use of Joint Sealants

– C1401 Standard Guide for Structural Sealant Glazing

– C1472 Standard Guide for Calculating Movement and Other Effects When Establishing Sealant Joint Width

• ASTM SSG Standards Compilation– ASTM Standards and Technical Articles Relating to Structural Sealant Glazing


• ASTM (www.astm.org)– E283 Standard Test Method for Determining the Rate of Air Leakage Through

Exterior Windows, Curtain Walls, and Doors Under Specified Pressure Differences Across the Specimen

– E330 Standard Test Method for Structural Performance of Exterior Windows, Curtain Walls, and Doors by Uniform Static Air Pressure Difference

– E331 Standard Test Method for Water Penetration of Exterior Windows, Skylights, Doors, and Curtain Walls by Uniform Static Air Pressure Difference

– E783 Standard Test Method for Field Measurement of Air Leakage Through Installed Exterior Windows and Doors

– E1105 Standard Test Method for Field Determination of Water Penetration of Exterior Windows, Skylights, Doors, and Curtain Walls by Uniform or Cyclic Static Air Pressure Difference


AAMA (www.aamanet.org)– 501.1 Standard Test Method for Water Penetration of Windows, Curtain

Walls, and Doors using Dynamic Pressure

– 501.2 Quality Assurance and Diagnostic Water Leakage Field Check of Installed Storefronts, Curtain Walls, and Sloped Glazing Systems

WBDG (www.wbdg.org)– 07 92 00 Joint Sealants, by The Adhesive and Sealant Council, Inc.

Journal of Building Enclosure Design

WBDGWHOLE BUILDING DESIGN GUIDE

Organizations

• ASTM Committee C24 on Building Seals and Sealants– (www.astm.org)

• Member companies of the Adhesive and Sealant Council– (www.ascouncil.org)

• American Architectural Manufacturers Association– (www.aamanet.org)

• National Institute of Building Sciences (NIST) – The Whole Building Design Guide web site– (www.wbdg.org)

WBDGWHOLE BUILDING DESIGN GUIDE

Acknowledgement

• The ASC graciously acknowledges the following member companies and other organizations for contributing to this presentation– Dow Corning Corporation

• (www.dowcorning.com)

– Momentive Performance Materials• (www.momentive.com)

– Tremco• (www.tremcoinc.com)

– SmithGroup• (www.smithgroup.com)

SSG

Documents

090428 Presentation Handouteoplugin.commpartners.com/ASC/090428/090428 Presentation Handout.pdf• Compatible one to the other Photos Courtesy SmithGroup Role of SSG Material Suppliers