Asphalt Shingle Application Requirements

Transcription

1 Alberta Allied Roofing Association Asphalt Shingle Application Requirements Section 1 Roof Decks 1.1 General Asphalt Shingles are not permitted to be installed directly over rigid insulation. When Asphalt shingles are applied over dimensional lumber it shall conform to ABC Section Roof Sheathing Table 6A. All lumber must be edge supported and have staggered lap joints. In re-roofing application the minimum thickness of the roof deck is to be 10mm (3/8 ) for both plywood and OSB roof decks. In new construction applications the roof sheathing shall conform to ABC Section Roof Sheathing Table 6A. This is dependant on the truss spacing and whether the edges are supported or not. 1.2 Strength Roof systems designs must meet the minimum requirements for dead & live loads as prescribed by the ABC Section 4.1 Structural Loads & Procedures. They must also be constructed to handle the loads during construction. Roof decks shall be free of damaged, deteriorated or decayed wood. 1.3 Surface The surface of the roof deck shall be sufficiently dry & clean to allow the proper attachment of the roofing system. The installation of a new roof over existing roofing material is not permitted. Old roofing materials are to be removed to expose the complete roof deck so that it may be inspected and repaired prior to the new asphalt shingles being installed. 1.4 Roof Slopes Sloped roofing relies on gravity to over come capillary action. Sloped roofs are designed to shed water and not be waterproof or watertight. On roofs with pitches equal to 4 in 12 (1:3) or more Standard Shingles shall be used.

2 On roofs with pitches less than 4 in 12 (1:3) and not less than 2 in 12 (1:6) Manufacturers methods of installation specific to the product are to be followed. Special Low Slope roofing materials may also be used provided they too are installed according to the manufacturer s directions. See attachment on Low Slope Application. Section 2 Roofing Materials 2.1 General The roofing materials shall conform to ABC Section and must conform to their applicable materials standard. All materials are to be labeled so that they are easily identifiable. 2.2 Protection & Storage All roofing materials that can be adversely affected by the weather must be protected until their time of installation. Only dry materials must be installed. Rolls of materials are to be stored on end, out of danger and protected until the time of installation. 2.3 Application Limitations All materials have physical limits as to what conditions they may be applied under. When the weather or conditions are present that could adversely affect the installation & performance of the products after they are installed, work must cease and only continue when the conditions are appropriate. 2.4 Asphalt Shingles Asphalt Shingles shall comply with CSA A Fasteners Nails used to attach asphalt shingles must be corrosion resistant roofing or shingle nails. Nails must be of sufficient length to penetrate 12mm (1/2 ) into the roof sheathing. The nails must have a head diameter not less than 9.5mm (3/8 ), a shank thickness of not less 2.95mm (1/8 ). Staples are not acceptable fasteners for AARA Contractor installations.

3 Section 3 Flashing at Intersections 3.1 Materials Sheet metal must conform to one of the following specifications: a) 1.73mm (1/16 ) thick sheet lead b) 0.33mm (13/1000 ) thick galvanized steel (30 Gauge) c) 0.46mm (18/1000 ) thick copper d) 0.46mm (18/1000 ) thick zinc e) 0.48mm (19/1000 ) thick aluminum (16 Gauge) 3.2 Valley Flashing Where roof planes meet to form a valley, the valley shall be flashed Open valleys shall be flashed with at least one layer of sheet metal not less than 600mm (2 ) wide or; When sheet metal is used as a valley flashing the use of an underlayment is recommended. (I.e. Self Adhered membrane (best), Reinforced Base Sheet (better), or 15# Asphalt Saturated felt (good)) When the pitches of the roof sections that meet in a valley vary in pitch significantly, the use of closed valleys (includes metal flashing ) or sheet metal with a 1 high center crimp ( W Valley) is recommended. Reference Alberta Building Code Section for minimum valley applications 3.3 Intersection of Shingle roofs and Walls Where a wall meets the roof deck flashing must be installed. Recommendation: 100mm (4 ) behind the sheathing paper and 100mm (4 ) horizontally. The head lap must also be no less than 75mm (3 ). Reference Alberta Building Code Section for minimum applications Where flashing is applied to an existing masonry wall or chimney counter flashing must be used and installed by the mason according to the Alberta Building Code (Pertains to New roof construction). For re-roof application, above section and gum lip flashing with caulking is acceptable.

4 3.4 Chimney Saddles When the upper section of a chimney is wider than 750mm (30 ) a chimney saddle must be installed. It is then to be flashed according to the valley & wall intersection details noted above. Chimney saddles are not required when the chimney is less than 750mm (30 ) wide, however the back pan flashing must extend up the chimney a minimum 1/6 th the width of the chimney but not less than 150mm (6 ). The back pan must also extend up along the roof slope to a point not less than the height of the back pan but never less than 1.5 times the shingle exposure. Section 4 Eave Protection 4.1 Materials a) Type M or S rolled roofing, with head and end laps cemented together. b) Minimum of glass or polyester fiber coated base sheets.(better) c) Self Adhering Modified bituminous membranes. (Best) Reference Alberta Building Code Section for minimum eave protection applications 4.2 Coverage Eave protection must extend from the roof edge a minimum of 900mm (3 ) but not less than to a point 300m (1 ) from the inside of the inner face of the exterior wall. Eave protection is not required but is recommended in good roofing practice a) Over unheated garages, carports & porches. b) Where the roof overhang exceeds 900mm (3 ) measured along the roof slope from the edge of the roof to the inner face of the exterior wall. c) On roofs where the slope is equal to or greater than 8 in 12 (1:1.5) It is recommended that drip edge flashing be used at the eaves & gable ends. This ensures proper drainage, prevents wicking into the sheathing and prevents wind driven moisture from infiltrating the fascia. When drip is used it should extend onto the roof deck a minimum of 75mm (3 ) and be spaced 6mm (¼ ) vertically from fascia on gable ends and 12mm (½ ) along the eaves. Good roofing practice recommends hemming exposed flashing edges for safety.

5 Section 5 Underlayment 5.1 Materials When underlayment is used beneath the shingles it shall be a minimum of 15# asphalt saturated felt that conforms to CSA A or asphalt saturated sheathing paper weighing not less than 0195 kg/m 2. Alternate underlayment may also be used such as self adhered membrane & glass fiber / polyester fiber coated base sheets. 5.2 Installation Underlayment shall be installed according the shingle manufacturers requirements. Fiberglass Shingled roofs must have underlayment installed to conform to CASMA Bulletin No. 22. Underlayment must be installed parallel to the eaves with a head and end lap of not less than 100mm (4 ). The underlay must also extend over the eave protection a minimum of 100mm (4 ). The top strip of the underlay shall be fastened so as to keep the material in place until it is shingled over. Underlayment must lie flat prior to shingle installation failure may result in the buckles telegraphing through the shingles. Section 6 Ventilation 6.1 General Attic space above an insulated ceiling must have adequate ventilation to prevent build up of condensation, prevent ice dams and prevent excessive roof heat which could prematurely wear out the shingles. 6.2 Calculation On roof slopes greater than 2 in 12 (1:6) roof exhaust and soffit intake are to be provided at a rate of 1 square foot of Net Free Area per 300 square feet of insulated ceiling space. On roofs with a slope of less than 2 in 12 (1:6) or roofs constructed with roof joists the rate is to be 1 square foot of Net Free Area for every 150 square feet of insulated ceiling space.

6 This is to be split evenly between the roof exhaust and the soffit intake, the ABC provides a tolerance of 25% either way in this system. For more specific ventilations requirements refer to Alberta building code Section 9.19 roof spaces 6.3 Materials Roof Exhaust vent may be of any design provided they prevent the infiltration of snow, rain & insects. They also must be of sufficient durability to survive the prevailing weather conditions. 6.4 Mansard & Gambrel Type Roofs The lower portion of these roof systems does not require venting. If the roof is over an attic space this upper portion shall be ventilated in accordance with this section. Section 7 Installation of Asphalt Shingles on Slopes of 4 in 12 (1:3) and Greater 7.1 Coverage Coverage shall be of not less then 2 thicknesses of shingles over the entire roof deck, disregarding shingle tab cut outs. 7.2 Starter Strip A Starter strip must be installed along the eave and gable fascia in such a manner that it extends a minimum of 12mm (1/2 ) beyond the eave and gable fascia. Fasteners shall be spaced not more than 300mm (1 ) O.C. Good roofing practice recommends starter shingles of the same weight and quality as those used as a roof covering with the tabs facing up the roof slope. 7.3 Head Lap Shingles shall have a head lap of not less than 50mm (2 ) 7.4 Fasteners Shingles shall be fastened with a minimum of 4 nail per 1m (3 ) wide shingle, except where noted below. Fasteners can be reduced in proportion to the shingle being installed when they are less than 1m (3 ) wide.

7 7.5 Securing of Tabs Shingle Tabs shall be secured by one of the following: a) Self sealing adhesive strips. b) By interlocking devices. c) By a spot of plastic cement about 25mm (1 ) in diameter under each tab for tab style shingles. d) By 3 spots of plastic cement about 25mm (1 ) in diameter placed evenly along the width for strip style shingles. Follow manufacturer s directions for winter installations. It may not be necessary to hand seal the shingles. Allow 1 season for sealing to complete. Proper nailing is the best way to defend against blow offs. 7.6 Hips & Ridges Shingles at the hips and ridges must be applied so that they extend a minimum of 100mm (4 ) on either side of the center point of the hip or ridge. Hip and ridge pieces must provide a minimum of 2 layers of coverage. Fasteners shall be placed to penetrate two (2) layers of hip or ridge pieces. Fasteners should be placed about 1 from the edge and 1 above the lap line on all hip or ridge pieces. Section 8 Asphalt Shingles on Slopes of 4 in 12 (1:3) to 2 in 12 (1:6) Refer to 1.4 Roof Slopes Concrete Tile See manufacturer s specification for all details of ABC Sheet Metal Roofing See manufacturer s specification for all details of ABC For more information contact: Alberta Allied Roofing Association P.O. Box RPO Crowfoot Calgary, Alberta T3G 3N8 Phone Fax aara@albertaroofing.com Website: