Normal Roof Slopes

The majority of north american residential roofs have historically been constructed with a slope between about 4 12 and 9 12.

Normal roof slopes.

A ratio is the most common way of expressing roof pitch or roof slope but degrees are also possible. This measurement is best done on a bare roof because curled up roofing shingles will impair your measurement. The minimum slope for lapped non soldered seam metal roofs without applied lap sealant shall be three units vertical in 12 units horizontal 25 percent slope. Pitches lower than 4 12 have a slight angle and they are defined as low slope roofs.

If the rise is 6 inches for every 12 inches of run then the roof slope is 6 in 12 the slope can be expressed numerically as a ratio. A pyramidal roof with gable ends. A roof that rises 4 inches for every 1 foot or 12 inches of run is said to have a 4 in 12 slope. The slope ratio represents a certain amount of vertical rise for every 12 inches of horizontal run.

Roofs at the lower end of the range about 4 12 to 6 12 are relatively easy to walk and work on. The picture below shows the pitch of a 7 12 roof slope meaning that for 12 of horizontal measurement roof run the vertical measurement roof rise is 7. Roof slopes between 4 12 and 6 12 are best for minimizing the wind uplift effects in high wind zones. 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.

The typical roof slope follows specific materials and design techniques to ensure perfect safety from leakage. Helm roof rhenish helm. A roof slope of 7 12 is also good and can provide the additional benefit of helping minimize the effects of wind driven rain. The most commonly used roof pitches fall in a range between 4 12 and 9 12.

The minimum slope for lapped non soldered seam metal roofs with applied lap sealant shall be one half unit vertical in 12 units horizontal 4 percent slope. Often found on church towers. Pitches above 9 12 are very highly angled and are designated steep slope roofs. A multi tiered and spired roof commonly found in burmese royal and buddhist architecture.

A handy roof slope estimator can help you determine if your roof slope is likely too low for shingles. Pitches of less than 2 12 are considered flat roofs even though they may be very slightly angled. You can also divide the rise over run multiply by 100 and get a percentage. According to this code the minimum slope for asphalt shingles is 17 degrees or two vertical units to twelve units in the horizontal.

A 4 12 pitch is around 18 5 degrees but not exactly. Tented a type of polygonal hipped roof with steeply pitched slopes rising to a peak. Thus a 4 12 pitch would be a 33 slope.