Key takeaways
- Flat roofs are low-slope, so drainage is the first design question.
- TPO is a reflective single-ply, EPDM is rubber and modified bitumen is layered.
- Seams and flashing are where most flat roofs fail.
- Regular checks and clear drains extend life.
Flat roofs are not really flat. They have a slight slope, and water leaves slowly, which makes drainage and seams the key details.
TPO
A white single-ply membrane with heat-welded seams. It reflects sunlight and is common on commercial buildings.
EPDM
A rubber membrane in large sheets with few seams. It has a long record on low-slope roofs.
Modified bitumen
Layers of asphalt-based rolls with a granulated surface. It is tough and handles foot traffic well.
Drainage
Ponding water is the enemy. Tapered insulation, drains and scuppers should carry water off, and they need to stay clear.
Care
Walk the roof twice a year, clear debris and look at seams, flashing and drains. A coating can extend the life of a roof that is still sound.
Related services
Questions about your own roof? Call or text 615-431-3789, or use the quote form below.