If you’re replacing a flat roof in Bristol, the choice usually narrows to two: traditional torch-on felt, or EPDM rubber membrane. Felt is what most older flat roofs already have; EPDM is what most of them get replaced with. Here’s the comparison played straight, including the cases where felt still makes sense.
Lifespan: the headline difference
Quality modern felt, properly installed, gives 10–20 years. EPDM realistically gives 40–50 — the material is a synthetic rubber that shrugs off the two things that kill felt: UV and thermal movement. Felt embrittles and cracks as sunlight cooks the bitumen; EPDM stays flexible from frost to heatwave. Over the life of a house, that’s one EPDM roof versus two or three felt roofs plus the repairs between.
Seams: where the leaks live
Felt is laid in overlapping strips, and every lap is a future maintenance point. On most domestic roofs, EPDM goes down as a single seamless sheet cut to size — the commonest failure mode simply isn’t there. Junctions and upstands still need doing properly on both systems (no membrane forgives lazy detailing), but the open field of the roof stops being a risk with rubber.
Cost: up front vs per year
Felt is cheaper to install — meaningfully so on small roofs. EPDM costs more per square metre but wins on cost per year of service by a wide margin, and it’s why we quote it as the default for flat roof replacement with a 20-year guarantee on installation. On a tight budget for a garage you plan to demolish in a decade, felt’s up-front saving is rational; on the flat roof over your kitchen extension, it usually isn’t.
Where felt still earns its place
Honest cases for felt: genuinely temporary buildings, complex roofs with many penetrations where a skilled felt detailer can work economically, and repairs to existing felt systems with life left (patching felt with felt is coherent; hybrid patchworks less so). There’s also appearance: some prefer felt’s mineral finish where a roof is overlooked, though slate-grey EPDM is hardly an eyesore.
Installation quality outranks material choice
A carefully-detailed felt roof outlasts a careless EPDM one. Whichever material you choose, the quote should name the product and spec, the edge and junction details, and the guarantee in writing — the usual rules from our quote-reading guide apply doubly to flat roofs.
Flat roof due a decision? Get in touch — we’ll assess what’s there and quote both honestly if it’s genuinely a toss-up.