What's the difference between TPO and torch-down?
There are two families on most Bay Area flat roofs. Single-ply membranes (TPO, PVC, EPDM) go down in large sheets with welded or glued seams. Asphalt-based systems (torch-applied or self-adhered modified bitumen, built-up roofing) go down in layers. Spray foam with a protective coating is a third route, common on some mid-century homes.
How long does each flat roof system last?
InterNACHI's estimates for flat systems vary widely (InterNACHI):
| Flat roof system | Estimated life (years) |
|---|---|
| Built-up roofing | 30 |
| Modified bitumen | 20 |
| TPO | 7 to 20 |
| EPDM rubber | 15 to 25 |
What drives the price of a flat roof replacement?
- Ponding fixes: tapered insulation, crickets, new drains
- Edges and walls: parapet flashing, coping, scuppers
- What's underneath: wet insulation or rotted decking found at tear-off
- Insulation upgrade: often worth doing now
- Getting materials up: stairs, hoists, shared walls
Does my flat roof need to be a cool roof?
Bayside cities such as Oakland, Berkeley, Hayward and Fremont are in climate zone 3, with no prescriptive low-slope cool-roof rule. Inland climate zone 12 cities such as Walnut Creek, Concord, Pleasanton and Livermore require a low-slope reroof to meet aged solar reflectance of 0.63 and thermal emittance of 0.75 (or SRI 75) unless an exception applies. See the CEC compliance manual.
What's different about flat roofs in the East Bay?
East Bay flat roofs are a mixed group: flat-roofed duplexes and fourplexes in Oakland and Berkeley, mid-century modern homes in the hills, Eichler tracts in Walnut Creek and Concord, and flat sections over additions and garages everywhere. The climate split matters. A flat roof in climate zone 12 inland usually needs a white or rated reflective membrane, while the same roof in Oakland doesn't. Hill homes add access challenges for rolls of membrane and debris.
How do I choose a system and a roofer?
Compare bids on the same system and thickness, how it attaches, how parapets and drains are detailed, insulation, and warranties. If torch-down is proposed, ask what fire precautions the crew follows and whether a torch-free alternative suits the edges. For your actual price, request a free written estimate: a licensed roofer measures the roof and prices your exact scope.
Related: what drives roof replacement cost, roof size estimator, dry rot and decking, quote checker.
Every roofer we work with is licensed, insured and highly reviewed by Bay Area homeowners.
Get a free replacement quoteFrequently asked questions
Is TPO better than torch-down?
Neither wins everywhere. TPO is reflective and welded; torch-down is a tough multi-layer asphalt system. Drainage, details and installation quality matter more than the label.
What should a flat roof bid include?
The membrane system and thickness, tear-off, insulation, drains and scuppers, parapet flashing, permit and warranty.
Does my Walnut Creek Eichler need a white roof?
A qualifying low-slope reroof in climate zone 12 generally needs a rated cool-roof membrane unless an exception applies. Ask the roofer to name the rated product.
Sources
- InterNACHI: life expectancy of roofing materials
- CEC 2025 Single-Family Compliance Manual, ch. 9
- California Residential Code R908 (reroofing)
- CEC: climate zones
Sources reviewed November 12, 2026. Figures are published estimates and official fees, not quotes. Confirm prices, permits and requirements with your contractor and building department. This page is general information, not legal or insurance advice.