Quick Answer
EPDM rubber roof is almost always the better choice when replacing an old flat roof in 2026. It costs £50–£80 per m² versus £40–£60 per m² for traditional felt, but lasts 30–50 years compared to 10–20 years for felt — making it significantly cheaper over the long term.
If you have a flat roof on a garage, extension, bay window, or outbuilding, you will at some point face the decision between felt and EPDM rubber as your roofing material. In 2026, this is not a close contest — but understanding exactly why EPDM wins, what it costs, and what the installation process involves will help you make the right choice and ask the right questions when getting quotes.
In this guide
What Is Felt Roofing and What Is EPDM?
Felt Roofing
Traditional felt roofing has been used on UK flat roofs for decades. Modern "felt" is mineral-surfaced bitumen felt (often called torch-on felt or SBS modified bitumen) — a significant improvement over the old 3-layer cold-applied felt, but still bitumen-based. It is installed in layers, with each layer torch-applied (heat-bonded) to the one below. Modern torch-on felt is a substantial product that performs well when correctly installed.
EPDM Rubber Roofing
EPDM stands for Ethylene Propylene Diene Monomer — a synthetic rubber compound. It comes in large single sheets (up to 15m wide) that are bonded to the roof deck with adhesive. The single-sheet design means far fewer seams and joints than multi-layer felt, which is where most flat roof failures begin. EPDM has been used on commercial flat roofs since the 1970s and is now standard practice for domestic flat roofs in 2026.
Full Comparison: Felt vs EPDM
| Factor | Felt (Torch-On) | EPDM Rubber |
|---|---|---|
| Typical lifespan | 15–25 years | 30–50 years |
| Cost per m² | £40–£60 | £50–£80 |
| Seams and joints | Multiple (failure points) | Minimal — large single sheet |
| UV resistance | Good (mineral surface) | Excellent — unaffected by UV |
| Temperature range | Moderate — can soften in heat | Exceptional (-45°C to +150°C) |
| Flexibility | Moderate | Very high — moves with structure |
| Installation method | Torch-applied layers | Bonded single sheet |
| Fire risk during install | Yes (naked flame) | None — cold adhesive |
| Repairability | Good — patches bond well | Excellent — self-adhesive patches |
| Appearance | Dark mineral surface | Dark grey/charcoal |
Cost Comparison in 2026
On a per-m² basis, EPDM costs £10–£20 more than torch-on felt. But the total cost picture is very different when you account for the lifespan difference:
| Roof Size | Felt Cost (2026) | EPDM Cost (2026) | 50-Year Cost Comparison |
|---|---|---|---|
| 20m² (garage) | £800–£1,200 | £1,000–£1,600 | Felt ~£2,400–£3,600 (2× replacements) vs EPDM ~£1,000–£1,600 (once) |
| 35m² (extension) | £1,400–£2,100 | £1,750–£2,800 | Felt ~£4,200–£6,300 vs EPDM ~£1,750–£2,800 |
| 50m² (larger extension) | £2,000–£3,000 | £2,500–£4,000 | Felt ~£6,000–£9,000 vs EPDM ~£2,500–£4,000 |
For full flat roof replacement costs including all the variables, see our dedicated guide: how much does it cost to replace a flat roof in the UK?
Installation Process
Both materials require stripping the existing roof covering and inspecting the roof deck (the timber boarding beneath). Rotten or damaged deck boards must be replaced before any new covering is laid. This adds to the cost but is not optional — laying a new membrane over a poor deck leads to early failure.
EPDM installation is generally quicker than multi-layer torch-on felt, and carries no fire risk during installation (torch-on felt uses a naked flame, which creates a small but real fire risk to the building). For common problems with existing flat roofs that might affect your decision, see our guide: flat roof problems: 7 most common issues.
Maintenance Differences
EPDM requires very little maintenance once installed. An annual visual check for debris buildup in drainage outlets and any obvious damage is all that is routinely needed. Self-adhesive EPDM patches repair small punctures or splits easily and permanently.
Felt flat roofs benefit from more regular checking — particularly at seams, around upstands and flashings, and at drainage outlets. Blistering is the most common felt issue and is usually caused by moisture trapped between layers during installation.
Which Should You Choose?
Choose EPDM for any flat roof you plan to keep for more than 10–15 years. The higher upfront cost is recovered within a few years compared to the shorter-lived felt alternative. The only scenario where felt might make more sense is if you are selling a property in the short term and want the cheapest option that passes a homebuyer survey.
If you are unsure what is already on your roof, our guide on how long a UK roof lasts covers the lifespan of all roofing materials. When you are ready to get quotes, see our guide to vetting a roofer to make sure you hire someone reputable.
Frequently Asked Questions
Can I lay EPDM over existing felt?+
Technically possible in some cases, but not generally recommended. Laying over existing felt means you do not get to inspect the deck condition, and any existing moisture is trapped. Most professional roofers will strip to bare deck before laying EPDM — this is the correct approach.
Is EPDM suitable for a roof I want to walk on?+
EPDM is not a walkable surface by design. For a roof terrace or a roof that will be walked on regularly, a different system is needed — GRP fibreglass with a non-slip coating, or a paving system on pedestals over the membrane. Ask your roofer about access requirements when quoting.
Does EPDM have a warranty?+
Most reputable EPDM products (RubberBond, Firestone, ClassicBond) come with manufacturer warranties of 20–50 years against manufacturing defects. Installation warranties from the roofer are separate and typically 5–10 years. Always ask for both.
What is GRP fibreglass roofing and how does it compare?+
GRP (Glass Reinforced Plastic) is another popular flat roofing material — it is applied as a liquid that cures to a hard, seamless surface. It has similar longevity to EPDM (25–40 years) and is arguably more visually neat. It costs similarly to EPDM. Both are significant improvements over traditional felt.
Can I repair a felt roof myself?+
Small temporary repairs to felt (applying cold-pour sealant or bitumen tape) can be done DIY but are rarely a long-term fix. If your felt roof is more than 15 years old and developing faults, replacement is almost always more cost-effective than continued patching.
Ready to get quotes?
Find a Flat Roofing Specialist Near You
Post your flat roof job on GetQuickHelp and get matched with qualified local roofers — free, no obligation.
Post Your Job Free →