Standard Garage Roof Slope

Simply put pitch is expressed as rise over run just as the grade is simply this fraction expressed as a percentage.

Standard garage roof slope.

There are advantages and disadvantages to having a steep pitch versus a shallow or low pitch. A 4 12 pitch is around 18 5 degrees but not exactly. A 4 12 is a roof slope that rises by 4 inches for every 12 inches across. You can assess this in two ways either as the roof pitch angles which the rafters make with the horizontal or the proportion between the run and the rise of the roof.

According to this code the minimum slope for asphalt shingles is 17 degrees or two vertical units to twelve units in the horizontal. Pitches lower than 4 12 have a slight angle and they are defined as low slope roofs. A 4 12 pitch being 4 inches of vertical rise over one foot or 12 inches of horizontal run. The requirements for an asphalt shingles roof are contained in the international building code.

Pitches of less than 2 12 are considered flat roofs even though they may be very slightly angled. This forms an angle of 18 5 between the horizontal section and the roof and creates a gentle incline that is seen as a midpoint between a low pitch and medium pitch roof. Roof pitch refers to the slope which the rafter creates. Pitches above 9 12 are very highly angled and are designated steep slope roofs.

Thus a 4 12 pitch would be a 33 slope. 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. You can also divide the rise over run multiply by 100 and get a percentage. The typical roof slope follows specific materials and design techniques to ensure perfect safety from leakage.

The most commonly used roof pitches fall in a range between 4 12 and 9 12. A ratio is the most common way of expressing roof pitch or roof slope but degrees are also possible. In roofing it is expressed in inches of vertical rise over inches of horizontal run.