ROOF CONSTRUCTION

The overall appearance of a building is greatly affected by the roof lines and the roofing materials. The designer has many standard designs to choose from and should be able to find one that will complement or add aesthetics to the building.

Roof Styles• Gable Roof

Popular design, easy to construct, sheds water well, easily ventilated and is applicable to a variety of house shapes and designs

• Hip RoofPopular design, complex to construct, easily ventilated when a ridge vent is used, sheds water well, creates an increased chance for leaks because of the hips and valleys

• Gambrel RoofSometimes referred to as a “Barn Roof”, has been used mostly on barns & sheds, provides lots of head room, easily ventilated, sheds water well

• Flat RoofMost economical, does not add much aesthetic appeal to the building, requires a “built-up”(layers of roofing felt and tar or other similar materials) or a membrane roof covering rather than conventional shingles, actually pitched 1/8” - 1/2” per foot for drainage, popular in warm areas of the country and on large buildings

• Shed RoofSimilar to flat roof, used on additions or in combinations with other roof styles, a built-up is required unless roof pitch is more than 3:12

Roof Truss Terminology• Roof Truss

An assembly made from 2 X 4’s that form one rigid roof component, spaced 2’ O.C., and can span distances of up to 32’ or more. Commonly used truss designs; King-post, W, & the Scissoro Information needed to purchase

the proper truss: span, roof pitch, spacing of trusses and anticipated roof load (a load of 40lbs. per square foot is adequate for most applications)

• Clear SpanThe horizontal distance from the inside of one studded wall to the inside of the opposing studded wall

• RiseThe vertical distance measured from the top of the double top-plate to the underside of the rafters

• RunHalf of the clear span

• GussetsMetal plates or pieces of plywood added to the truss’s joints to provide extra strength

Stick Framed Roof Terminology• Ridge Board

Horizontal component positioned on its edge at the ridge (middle) of the roof & is an anchor place for the upper ends of the rafters

• Common RafterDiagonal component spaced 16” or 24” O.C. spanning from the ridge to the double top plate of an exterior wallo Cut to proper dimension by locating the ridge cut, seat cut, plumb cuts, and tail cut. The

precise layout of these cuts is determined by the slope or pitch of the roof and the inside width or clear span of the building.

• Collar TieHorizontal component connecting two opposing rafters

• Hip Jack Rafter (for hip roofs only)Same as common rafter except it does not extend all the way to the double top plate of an exterior wall

• Hip Rafter (for hip roofs only)Diagonal support spanning from the end of the ridge board to the double top plate of an exterior wall corner

• Hip Jack Rafter (for hip roofs only)Same as a common rafter except it extends from the hip to the double top plate of an exterior wall

General Roof Terminology• Overhang/Cornice

The overhang of the roof at the eaves line that forms a connection between the roof and the side wall

• Closed CorniceNo overhang, just the trim that finished out the roof

• Open Cornice/Wide Box with LookoutsRequires additional support members (lookouts) for fastening the soffit

• Rake or Gable EndThe extension of a gable roof beyond the end wall of the house, which should be equal to the overhand at the eaves line

• VentilationProper air flow throughout the underside of a roof so moisture/mold does not form and help preserve the life of the shingles

• GuttersTroughs that carry water runoff from the roof to the downspouts, preventing water from running directly off the eaves and splattering the house and running down the foundation wall potentially causing leaks in the basemento Are generally pitched 1” to 1-1/2”

in a 20’ span

DownspoutCopper, vinyl, aluminum, and galvanized sheet metal rectangular shaped pipe used for carrying rainwater from the gutters down to the ground and away from the building

Roof SheathingThe board or sheet material fastened to the roof rafters/trusses providing strength to the roofing system and a surface for the roofing materials

• Sheets must be staggered so that two sheets side-by-side do not end on the same rafter

• The most common type of roofing material is asphalt shingles

• A square of shingles covers 100sq.ft.

• Other materials used for roofing include: wood shingles, tile, slate, roll roofing, copper/aluminum/galvanized steel, layers of felt and tar and rubber membrane roofing

• Factors that influence the selection of the roofing material are: cost, local codes, roof pitch, design of house and individual preference

RoofingMaterial used on top of the roof sheathing which provides a waterproof barrier.

• Ice Guard then Building Paper should be placed on top of the sheathing first to act as an ice barrier and moisture barrier

Works CitedKicklighter, Clois E., Ronald J. Baird, and Joan C. Kicklighter. Architecture: Residential Drawing and Design. South Holland, IL: Goodheart-Willcox, 1995. Print."Owens Corning 30 Year Architectural Shingles." Owens Corning 30 Year Architectural Shingles. N.p., n.d. Web. 14 Dec. 2012."San Diego Roofer and General Contractor: Why San Diego Roofs Love Asphalt Shingles." San Diego Roofer and General Contractor: Why San Diego Roofs Love Asphalt Shingles. N.p., n.d. Web. 14 Dec. 2012."Types of Prefab Roof Trusses." Types of Prefab Roof Trusses. N.p., n.d. Web. 14 Dec. 2012."Walker Roofing & Exterior." Walker Roofing Exterior. N.p., n.d. Web. 14 Dec. 2012.https://www.studyblue.com/notes/note/n/dhe-180-midterm-2/deck/2329721http://www.hungryarchitect.com/blog/?p=901http://roofing.lifetimewarrantyfence.com/frisco/layers-of-a-roofing-system/http://www.designroofingwv.com/residential.html