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 Roof Popular 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 Roof Sometimes referred to as a Barn Roof, has been used mostly on barns & sheds, provides lots of head room, easily ventilated, sheds water well
Flat Roof Most 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 Roof Similar 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 utilizing a minimum amount of vertical, horizontal and diagonal 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 Scissor o 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 Span The horizontal distance from the inside of one studded wall to the inside of the opposing studded wall Rise The vertical distance measured from the top of the double top-plate to the underside of the rafters Run Half of the clear span Gussets Metal 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 Rafter Diagonal component spaced 16 or 24 O.C. spanning from the ridge to the double top plate of an exterior wall o 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.
Jack Rafter Same as common rafter except it does not extend all the way to the double top plate of an exterior wall Hip Board (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 Collar Tie Horizontal component connecting two opposing rafters
Cornice/Overhang The overhang of the roof at the eaves line that forms a connection between the roof and the side wall Closed Cornice No overhang, just the trim that finished out the roof Open Cornice/Wide Box with Lookouts Requires additional support members (lookouts) for fastening the soffit
Rake or Gable End The extension of a gable roof beyond the end wall of the house, which should be equal to the overhand at the eaves line Ventilation Proper air flow throughout the underside of a roof so moisture/mold does not form and help preserve the life of the shingles Flashing Sheet metal (aluminum, copper & galvanized steel) attached where the roof comes in contact with a wood or masonry wall, chimney, or roof valley to protect the building from water seepage Gutters Troughs 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 basement o Are generally pitched 1 to 1-1/2 in a 20 span
Downspout Copper, 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 Sheathing The 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
Roofing Material used on top of the roof sheathing which provides a waterproof barrier. 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 Ice Guard then Building Paper should be placed on top of the sheathing first to act as an ice barrier and moisture barrier
Works Cited Kicklighter, 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.