If your flat roof is leaking or past its best, the first decision is what to replace it with. For most homes that comes down to two options: EPDM rubber or torch-on felt. We fit both, so this guide isn't here to sell you one over the other. It explains how each works, where each one does well, and what matters more than the material itself.
What is an EPDM rubber roof?
EPDM is a flexible synthetic rubber membrane. On a straightforward roof it can often be laid as a single sheet, which means few or no joints across the main area. It's bonded to a prepared deck with adhesive, then finished with trims at the edges and details around outlets and walls. Because it's fitted cold, there's no naked flame on the roof.
What is a torch-on felt roof?
Torch-on felt uses layers of bituminous felt, bonded to the roof and to each other with heat from a gas torch. The top layer usually has a mineral finish to protect it from the sun. It's a long-established system, and it's a long way from the older felt roofs many homes still have, which is often what people are picturing when they say felt doesn't last.
Pros and cons
EPDM rubber
• Largely seamless on simple roofs, so fewer joints where water can get in
• Flexible, so it copes well with movement and changes in temperature
• Fitted cold, with no flame on the roof
• Correctly specified and installed, it can provide 20+ years of service
• Needs dry conditions and a clean, smooth deck for the adhesive to bond properly
• A sharp object can puncture it, although small damage can usually be repaired
Torch-on felt
• Long-established and hard-wearing, with a mineral surface that protects it from the sun
• Built up in layers, which suits roofs with plenty of details and upstands
• Can be patched and repaired
• Depends on well-made laps and edges, because the joints are where it's most at risk
• Uses heat on site, so it needs care around timber, fascias and other materials
Which suits your roof?
For a simple extension, garage or dormer, EPDM is often a good fit: a clean, largely seamless finish with very little to maintain. Felt can suit roofs with lots of details, or where it matches or connects to an existing felt roof. The right answer depends on the shape of the roof, what it joins on to, and how it's used. We'll look at yours and explain the options honestly. For smaller roofs, see our page on porch and garage roofs.
What matters more than the material
Most flat roof problems we're called out to aren't about the membrane in the middle of the roof. They start at the edges, outlets and the joins to walls. Whichever covering you choose, three things decide how well it performs:
• A sound deck. If the boards underneath are soft or damp, they need replacing first. A new covering on a rotten deck won't last.
• Proper falls. Flat roofs aren't truly flat. They need a slight slope so rain runs towards a gutter or outlet rather than sitting on the roof.
• Good detailing. Edge trims, outlets and upstands are where water gets in, and where a roof is won or lost. Where a flat roof meets a wall or a chimney, leadwork is often part of a proper job.
Signs your flat roof needs replacing
• Leaks that keep coming back after repairs
• Blisters, splits or cracks in the covering
• Water sitting on the roof long after the rain has stopped
• A soft or spongy feel, which can mean the deck has failed
• Damp patches or staining on the ceiling below
One small leak doesn't always mean a new roof. It's often worth having it inspected first. If you've got water coming in now, read what to check if your roof leaks after heavy rain.
Do you need permission to replace a flat roof?
Replacing a flat roof like for like usually doesn't need planning permission, but there are exceptions, and larger replacements can bring Building Regulations into play. Our planning permission guide explains what to check.
What our customers say
Sam F. had an EPDM roof fitted in Peterborough: "Danny and the team came and fitted a EPDM rubber roof for me in Peterborough. Really happy with the finish and the overall service was professional. I would recommend."
Get a free flat roof inspection
DJW Roofing & Leadwork fit EPDM rubber and torch-on felt flat roofs across Ely, King's Lynn, Peterborough and the surrounding areas. We offer free inspections and quotes, and all our work is fully insured and guaranteed. Call 07862 885143 or request a free quote.
Frequently asked questions
Is EPDM better than felt?
Neither is best for every roof. EPDM is often a good choice for simple extensions, garages and dormers because it can be largely seamless. Torch-on felt can suit roofs with more details. The deck, falls and detailing matter as much as the covering.
How long does an EPDM roof last?
Correctly specified and installed, EPDM can provide 20+ years of service. That's an expectation rather than a fixed guarantee period, so ask about the details for your own roof.
Can a new flat roof go over the old one?
We check the existing covering and the deck first. Where the deck is soft or damaged, the old roof needs to come off so it can be repaired or replaced before the new covering goes on.
Can you walk on a flat roof?
Flat roofs are generally made for occasional access, such as maintenance, and not as a walkway or terrace. If you need regular access, tell us before work starts so it can be planned for.
Can a leaking flat roof be repaired rather than replaced?
Often, yes, especially where the leak is at an outlet, edge or joint and the rest of the roof is sound. We'll inspect it and tell you honestly whether a repair makes sense.