

CALL/TEXT 757-450-5540
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Waste Pipe = ¼ inch per foot (0.25) minimum & 3 inches per foot maximum or vertical
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Gas Vent = ¼ inch per foot (0.25) with minimum rise of 1 foot above draft hood before an elbow
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Roof with shingles:
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4inches per foot (4/12)
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With Double Ice Shield (2 – 4 per 12)
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Maximum Slope:
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Asphalt shingles should not be installed on vertical walls.
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> 12/12 to 18/12
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6 nails per shingle
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Hand sealing or "tabbing" roof shingles on a steep slope means applying a dab of sealant (roof cement) under each shingle. For architectural-style laminated shingles use four equally-spaced dabs of sealant under the shingle's leading (lower) edge.
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Gutter = ½ inch per 10 feet (0.05) with runs no greater than 40 feet
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Grade = 6 inches per 10 feet (0.6)
Loading
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Downspout (2x3 typical….3x4 & 3x4 diverter multiple by 2) = 1200 sq ft (1 inch rain/hr)
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It is based on the assumption that during a rainfall with an intensity of 1 inch per hour, each square inch of downspout can drain 1200 square feet of roof. If the intensity is doubled the downspout capacity is halved, or 600 sq. ft.; if it is tripled the capacity is one third, and so on.
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Venting
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Crawl
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Poly = 1 sq foot per 1500 sq ft
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No Poly = 1 sq ft per 150 sq ft
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One square foot of net free vent area is recommended for every 1500 square feet of floor area covered by a polyethylene vapor retarder. Ratio is 1:150 if vapor retarder is not used.
*Net free vent area is that area unobstructed by screens, louvers, or other materials.
*Heated crawlspaces and basements do not need vents.
Earth floors should be covered with a 4 - 6 mil. polyethylene vapor retarder.
*Providing at least two crawlspace vents will allow for a flow of air in and out of the crawlspace
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Roof = 1 sq ft per 150 sq ft divided evenly between soffit and roof peak
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Pipe Hangers
Most plumbing codes have the following hanger spacing requirements: ABS and PVC pipe have a maximum horizontal hanger spacing of every four feet for all sizes. CPVC pipe or tubing has a maximum horizontal hanger spacing of every three feet for one inch and under and every four feet for sizes 11⁄4 inch and larger.