Low Slope Roof Ratio

Coffman p e secb and thomas g.

Low slope roof ratio.

Position your level against the roof until the bubble of the vial sits between two lines. The short simple answer is 2 12 has traditionally been considered the absolute minimum acceptable roof slope suitable for asphalt shingles. Minimum roof slope of 0 5 12 for lapped nonsoldered seam metal roofs with lap sealant applied minimum roof slope of 0 25 12 for standing seam roof systems modified bitumen roofing should be installed on roof slopes 0 25 12 or greater 2015 irc r905 11 1. Slope is calculated by rise over run thus a low sloped roof is a roof where for every 12 units inches feet or meters measured horizontally run the roof does not increase or decrease by more than 4 units vertically rise.

Check the surface of the. In either case find a professional roofing contractor experienced with low slope roofs and these specific products. What is the minimum slope for an asphalt shingle roof. 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.

Slope is conveyed as a ratio and it stands for an amount of vertical rise for every 12 inches of a horizontal run which is again expressed as 3 12 or 3 in 12. A low sloped roof is defined as a slope equal or less than a ratio of 4 to 12. A 4 12 is a roof slope that rises by 4 inches for every 12 inches across. And steep slope roofing which is above 9 12 3 in 4 21 12 7 in 4 and may require extra fasteners.

Conventional from 4 12 1 in 3 to 9 12 3 in 4. Most low slope roofs have a slope of less than 3 in 12 which means that a roof that rises 3 inches for every foot of run will be defined as one that has a 3 in 12 slope. The basic ranges of pitch are not uniformly defined but range from flat which are not perfectly flat but sloped to drain water up to 1 2 12 to 2 12 1 in 24 to 1 in 6. As in all construction work paying attention to the little details can make all the difference between a long lasting trouble free project and one that results in callbacks and early failure never a good option with a new england roof.

Low slope roofing which requires special materials and techniques to avoid leaks and ranges from 1 12 2 12 to 4 12 1 in 3. Take a measurement of 12 inches using a level. Chapter 15 in the 2015 2018 international building code ibc contains installation guidelines that permit a design slope of 1 4 in 12 for certain types of roof covers. Specifically the code text typically reads.

Many roofing shingles do not allow applications onto roofs at this pitch. Design solutions for building code permitted low slope applications that cause ponding water. Before taking any measurements you must first confirm that it s safe to walk on your roof. Asphalt shingles continue to be the most widely installed roof covering option in north america.