Is single ply membrane better than felt?

For most roofs, yes. Felt is built up from layers bonded or torched together, and its laps are the part that splits and lets water in as it ages. Single ply is a single sheet whose seams are hot-air welded into one continuous skin, so there is far less to fail. It also lasts longer and needs no naked flame to install.

How much longer does single ply last than felt?

Traditional felt typically lasts around 10–15 years. A quality single ply membrane carries a 20–25 year manufacturer guarantee and often lasts longer in practice, so it usually doubles the life of the roof for a modest extra cost up front.

Is single ply more expensive than felt?

Felt is usually cheaper on day one. Single ply costs a little more to fit, but spread over its much longer life it normally works out better value, because you are not paying to strip and re-cover the roof again in ten years.

Can you install single ply over an existing felt roof?

Sometimes, if the deck and insulation underneath are sound and dry. We confirm at the free survey whether an overlay is suitable or whether a full strip and refit is the better long-term answer for your roof.

Do you fit single ply flat roofs in Doncaster?

Yes. We are based in Armthorpe and install single ply flat roofs across Doncaster, Rotherham, Barnsley, Mexborough and the surrounding South Yorkshire towns. You can see the full list on our areas we cover page.

Single Ply vs Felt Flat Roofing: Which Is Best?

If you’re replacing a flat roof in Doncaster, you’ll quickly come across two very different options: traditional felt (built-up roofing) and modern single ply membrane. Both keep the rain out on day one, but they don’t age the same way, and over twenty years the difference is stark. Here’s an honest comparison from a team that has fitted single ply since 1995.

What is felt roofing?

Felt, or built-up roofing, is the system most people picture when they think of a flat roof. Layers of bitumen-based felt are bonded together, traditionally using a gas torch (“torch-on” felt). It’s a long-established method and the up-front cost is usually low, which is why it still gets specified on tight budgets.

The downsides are well known. Felt has a relatively short life, and its seams and laps are the common failure point. Older felt also blisters, cracks and goes brittle as the sun and frost work on it, and the torch-on process brings a naked flame onto your property. Once a felt roof starts to fail, it tends to fail in several places at once.

What is single ply membrane?

Single ply is a single sheet of high-performance waterproof membrane, usually PVC or TPO, laid over insulation and either mechanically fixed or fully bonded to the roof. The detail that changes everything is the seams: they’re hot-air welded, fusing the sheets into one continuous, joint-free skin. A properly welded seam is actually stronger than the membrane around it.

That one difference matters enormously. With no torched or glued laps to fail, there’s simply far less to go wrong. Single ply is the system used on the vast majority of modern commercial buildings for exactly this reason, and it works just as well on a house, an extension or a garage.

How they compare

Lifespan: Felt typically lasts around 10–15 years. A quality single ply membrane carries a 20–25 year manufacturer guarantee and often lasts longer.
Reliability: Welded single ply seams are stronger than the surrounding sheet. Felt laps are the weak point, and they are where leaks start.
Safety: Single ply is welded with hot air, so there’s no naked flame near an occupied home, school or commercial unit.
Appearance: Single ply lays flat and clean, with neat detailing around upstands, outlets and rooflights.
Cost: Felt is cheaper up front. Single ply costs a little more but, spread over its much longer life, usually works out better value.

What about EPDM rubber and GRP fibreglass?

Felt isn’t the only alternative you’ll be quoted for. EPDM rubber and GRP fibreglass come up too, and both share felt’s basic weakness: their joints and details are the part that fails. EPDM relies on glued seams and tapes that perish with age, while rigid GRP can craze and crack where the deck moves beneath it. Single ply sidesteps both problems because its seams are welded and the membrane stays flexible. We’ve set out the full picture in our guide to EPDM vs GRP vs single ply.

So which should you choose?

For most homeowners and businesses we’d recommend single ply membrane. The longer life, welded seams and proper manufacturer guarantee mean fewer call-backs and better value over time. It’s just as at home on a domestic extension, dormer or garage as it is on a commercial unit.

Felt can still make sense on a tight budget or a small, simple roof, and we’ll always give you a straight answer about what’s right for your project rather than push the dearest option. If lifespan is your main concern, our guide to how long a flat roof lasts goes into more detail.

Single ply flat roofing across Doncaster and South Yorkshire

We’re based in Armthorpe and fit single ply flat roofs on homes and businesses right across the region, from Doncaster town centre to Rotherham, Barnsley, Mexborough and the villages in between. Whether it’s a tired felt garage roof in Bessacarr, an extension in Bawtry or a commercial unit near the M18, we specify the membrane that suits the roof and weld it into a covering that lasts. You can see every area we cover on our areas page.

Want a recommendation for your roof? Get a free quote or call us on 07973 436 305.