Side by side
| Spray foam + coating | TPO membrane | |
|---|---|---|
| Seams | None | Heat-welded |
| Insulation | Built in | From board underneath |
| Fixing slope | Spray thicker where needed | Tapered insulation board |
| Parapets | Foam cant, seamless | Membrane wrapped and terminated |
| Upkeep | Recoat every several years | Inspect seams and flashing |
| Repairs | Patch foam, recoat | Weld a patch |
Foam makes sense when
- You want added insulation without much weight
- The roof has lots of parapets, cooler stands and odd shapes
- Ponding needs fixing
- You're OK with recoating on a schedule
TPO makes sense when
- The old roof is coming off anyway
- You want a membrane that doesn't need a recoat cycle
- The roof is fairly simple and open
We install both and will tell you which we'd choose for your roof. See flat roof replacement.
Roofing questions
Which lasts longer?
Both can last many years. Foam's life depends on keeping the coating up.
Which costs less?
It depends on the roof; ranges overlap. We'll price both if you like.
Can I switch from foam to TPO?
Yes, usually with removal or a cover board.