EPDM vs Felt: Modern Flat Roofs Explained
Felt flat roofs used to be the standard — they were also the standard reason for ten-year leaks. EPDM single-ply rubber has now taken over for almost every flat-roof project we do. Here's why, and the edge cases where felt still wins.
EPDM Rubber
Almost every modern flat roof up to 12m span.
- Single seamless sheet on most domestic spans
- 25-year manufacturer warranty
- Cold-applied — no torches near eaves
- UV-stable for 30+ years
- Higher cost than felt
- Specialist install — not a DIY material
Built-up Felt
Tight-budget garage roofs and short-term repairs.
- Lowest cost
- Quick install
- Widely understood — any roofer can fit it
- 10–15 year lifespan
- Blistering and seam-failure common
- Requires hot torch (fire risk near eaves)
GRP Fibreglass
Complex flat roofs with walk-on use, balconies, parapets.
- Seamless, follows complex shapes
- Walk-on rated
- 20+ year lifespan
- Weather-sensitive install
- More expensive than EPDM
Our honest verdict
Default to EPDM for any new flat roof you intend to keep for 20+ years. Felt is now only the right answer if you genuinely need the cheapest possible 10-year fix. GRP is the right answer for balconies and complex parapet roofs.
Local angle
Across Lancashire we now fit EPDM on 9 out of every 10 flat-roof jobs. Felt only goes on outbuildings where the owner is explicit about budget over longevity.
Can EPDM go straight over my old felt roof?
Sometimes, if the deck below is sound and dry. We always strip back at least the eaves and check the deck — overlay only goes ahead if the deck passes a moisture test.