How Much Grade Do I Need On Roof

Minimum roof pitch for shingles.

How much grade do i need on roof. The majority of north american residential roofs have historically been constructed with a slope between about 4 12 and 9 12. To estimate roofing materials start by finding the total square footage of the roof and divide the number by 100 to determine the number of squares in the roof. Outside of the u s a degree angle is typically used. The tools required will be a contractor s level at least 24 inches long and a tape measure.

Roofs at the lower end of the range about 4 12 to 6 12 are relatively easy to walk and work on. A handy roof slope estimator can help you determine if your roof slope is likely too low for shingles. Common roof pitches and equivalent grade degree and radian angles. Place the butt end of the level against the edge of the roof and extend it into the air balancing it until it becomes level.

Since it takes 3 bundles of shingles to cover a square plan to purchase 3 bundles for each square. Then add 10 to the number to account for waste. 4 12 to 20 12 pitches. The irc recommends a minimum design load of 10 pounds per square foot in addition to all dead loads except where this minimum is exceeded by local snow or wind load requirements.

Slopes above 19 12 are not recommended since tiles on very steep roofs can rattle. Patio cover roofs must conform to the local building code including how they are attached to the building. In roofing it is expressed in inches of vertical rise over inches of horizontal run. The table below shows common roof pitches and the equivalent grade degrees and radians for each.

A 4 12 pitch being 4 inches of vertical rise over one foot or 12 inches of horizontal run. Clay or cement tiles can be used on a wide range of roof pitches. The most common rafter spacing is 24 inches and 5 8 inch plywood is recommended for that. Simply put pitch is expressed as rise over run just as the grade is simply this fraction expressed as a percentage.

For pitches of 2 5 12 up to 4 12 the roof requires double underlayment. A pitch over 9 12 is considered a steep slope roof between 2 12 and 4 12 is considered a low slope roof and less than 2 12 is considered a flat roof. For instance a 7 12 roof pitch means that the roof rises 7 inches for every 12 horizontal inches. There are advantages and disadvantages to having a steep pitch versus a shallow or low pitch.

If not you will need to make your measurement from on top of the roof itself or at the edge of the roof with a ladder. Most roof s have a pitch in the 4 12 to 9 12 range. With regards to the pitch the building standard code bs 5534 recommends a minimum pitch of 200 for slate roofs.