Roofing Slope Standards

Steep slope roofs have the greatest pressures in the perimeter and corners as well as the roof peak and eaves.

Roofing slope standards.

California roofing codes establish a list of rules that all builders and contractors must adhere to in order to ensure safe building practices within the state. D5869 d5869m 07a 2018 e1. Standard test method for granule adhesion to mineral surfaced roofing by abrasion. It is the recommended slope as there is no guarantee if you opt for flatter pitch than this.

Asphalt shingles are appropriate on roofs with conventional pitches between 4 12 and 9 12. The new cool roof requirements affect new construction significant repairs of existing roofs re roofing plus additions and alterations of existing buildings and homes. Standard specification for asphalt saturated organic felt underlayment used in steep slope roofing. A common range is given from 1 12 to 4 12 whereas conventional dimensions vary from 4 12 to 9 12 but the steep roofing technique follows slope above 9 12 with additional fasteners.

Standard practice for dark oven heat exposure of roofing and waterproofing materials. The typical roof slope follows specific materials and design techniques to ensure perfect safety from leakage. The specifically stated intent of this specification is to provide criteria for producing and evaluating underlayments with a significantly reduced tendency to wrinkle before or after the installation of steep slope roofing products. The corrugated metal roof minimum slope is 5 degrees.

Asphalt saturated felt starting at the eaves and lapping upper courses over lower by a minimum of 2 inches. You need to consider the slope requirements of each panel to determine this minimum slope. The profile is the shape taken by the sheets when you bend them to form panels. Corrugated roofing is an amazing choice for conventional pitched roof despite having the severe limitation about the pitch.

Astm d6757 standard specification for underlayment felt containing inorganic fibers used in steep slope roofing addresses inorganic fiber reinforced organic felt underlayment and inorganic fiber based felt used as underlayment in steep slope roof systems. Vertical joints should lap a minimum of 4 inches and be offset by at least 6 feet in successive rows see figure 2 2. D4977 d4977m 20. Low slope or flat roofs should not be roofed with asphalt shingles because it is much easier for water to infiltrate the roofing material on a roof with a shallow pitch.

As of january 1 2010 the california energy commission s updated title 24 building energy efficiency standards for residential and non residential roofing are now in force otherwise know as cool roof. D6380 d6380m 03 2018. On roofs with a slope of 4 12 or greater use a single layer of 15 lb. Zoning can also vary based on roof slope and geometry e g low slope versus steep slope or gable roof versus hip roof.

For low slope roofs wind pressures typically have the greatest magnitude at the roof perimeter and corners.