What is a “flat” roof?
Most “flat” roofs are low‑slope roofs designed to drain water. Proper slope and drainage are essential.
Common systems
TPO/PVC single‑ply membranes, modified bitumen (APP/SBS), and built‑up roofing are common choices.
Key components
Membrane, insulation, cover board, flashing, drains/scuppers, and edge metal all work together.
Repairs vs replacement
Small punctures or flashing issues may be repairable. If the membrane is aged and seams fail repeatedly, replacement may be smarter.
Best practices
Prioritize drainage, quality flashing, and compatible materials to avoid leaks.
FAQ
Quick answers to the most common questions.
Why do flat roofs leak? +
Most leaks come from flashing details, penetrations, ponding water, or aging seams—not the field membrane itself.
Is TPO good for the Bay Area? +
TPO can perform well when installed correctly with proper insulation and detailing, especially in sunny areas.
How often should a flat roof be inspected? +
At least once per year and after major storms or wind events.