Flat Roofing
Flat and low-slope roofs are common on modern LA homes and additions. They require different materials and more attention to drainage than pitched roofs.
How Flat Roofing Works
A flat roof isn't truly flat — it has a slight slope (usually 1/4 inch per foot) to allow water to drain. The key difference from pitched roofing is the membrane system used to waterproof the surface. Choosing the right membrane and maintaining proper drainage are the two most important factors in flat roof performance.
The Three Main Flat Roof Systems
TPO (Thermoplastic Polyolefin)
The most popular flat roofing material today. White or light-colored, which reflects heat well — a big advantage in LA summers. Seams are heat-welded for a strong bond. Lifespan of 15–25 years.
EPDM (Rubber Roofing)
A durable synthetic rubber membrane. Usually black, which absorbs heat. Very resistant to UV and ozone. Seams are glued or taped. Lifespan of 20–30 years with proper maintenance.
Modified Bitumen
An asphalt-based system applied in layers. Often used on roofs with complex penetrations (vents, HVAC units). Torch-applied or self-adhering. Lifespan of 15–20 years.
What Does Flat Roofing Cost?
Flat roofing costs vary by system type and roof size. In the LA area, expect to pay between $6,000 and $18,000 for a typical flat roof replacement. Drainage improvements and deck repairs can add to the total.
What to Ask Before You Sign
- What membrane system are you recommending and why?
- How will drainage be addressed — are drains and scuppers included?
- Will the existing membrane be removed or will you install over it?
- What is the warranty on the membrane and on the labor?
- How do you handle penetrations like vents, pipes, and HVAC curbs?
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