Which slope is indicated for thermoset single-ply membranes as not less than?

Which slope is indicated for thermoset single-ply membranes as not less than?

• A. 1/8:12
• B. 1/4:12
• C. 1:12
• D. 1:6

Answer: (B)

The thing being tested is the minimum roof slope needed to properly drain thermoset single-ply membranes. For this type of membrane, you want enough slope so water doesn’t pond on the surface, which can weaken seams and shorten life. The standard minimum is 1/4 inch of rise for every 12 inches of run, written as 1/4:12, which is about a 2% grade. This ensures water will flow toward drains or edges rather than ponding. The other options represent either too little slope to reliably drain water or a slope that's much steeper than the typical minimum, so they don’t represent the required not-less-than value.

The thing being tested is the minimum roof slope needed to properly drain thermoset single-ply membranes. For this type of membrane, you want enough slope so water doesn’t pond on the surface, which can weaken seams and shorten life. The standard minimum is 1/4 inch of rise for every 12 inches of run, written as 1/4:12, which is about a 2% grade. This ensures water will flow toward drains or edges rather than ponding.

The other options represent either too little slope to reliably drain water or a slope that's much steeper than the typical minimum, so they don’t represent the required not-less-than value.