A low-slope roof is a nearly flat roofing system that rises 2 inches or less for every 12 inches of horizontal run. Because water drains slowly off these surfaces, they cannot rely on overlapping materials like shingles. Instead, they require continuous, watertight membranes such as EPDM, TPO, or built-up roofing to prevent leaks.
Heard on the job
We can't use asphalt shingles on that addition, it's a low-slope roof and needs a rolled membrane.
Also heard as
- flat roof
Do not mix it up with
- Steep-slope roof: Low-slope roofs require sealed membranes because water drains slowly, whereas steep-slope roofs shed water quickly using overlapping shingles.
Related terms
Steep-slope roof
A roof surface installed at a pitch of 2:12 or greater.
Built-up roof
A flat roof covering made of alternating layers of bitumen and reinforcing fabrics.
Roof assembly
The complete system of interacting components that form a building's roof, from the structural deck up to the weatherproofing layer.