Thetford Roofers installs and replaces flat roofs on extensions, garages and bay windows for homeowners in Bury St Edmunds and the surrounding area.
When a flat roof fails, you have a genuine choice about what goes back on. The system you pick affects how long it performs, what it costs to maintain, and how easy it is to repair if something goes wrong later. Understanding the honest pros and cons of each option helps you make a decision you won't regret.
The three systems most commonly used on domestic flat roofs in the UK today are built-up felt, torch-on felt, and EPDM rubber. Each suits different situations, and none is right for every job.
Traditional built-up felt uses multiple layers bonded together, typically three, to create a waterproof covering. It has been used on British roofs for decades and most experienced roofers can work with it.
The main advantage is cost. Built-up felt is the least expensive system to install, which makes it attractive for smaller jobs such as a bay window or a garden room roof where budget is the primary concern. On a straightforward surface with no penetrations or complicated upstands, it can perform adequately.
The honest downside is longevity. A well-installed three-layer felt roof can last around ten to fifteen years before it starts to crack, blister or let water in at the joints. Felt is also more vulnerable to frost damage and UV degradation than the alternatives. If your flat roof is over a heated kitchen extension, thermal movement can work the felt loose at the edges over time.
Torch-on felt, sometimes called SBS or polyester-reinforced felt, is a step up from traditional built-up felt. It uses a gas torch to bond the material rather than cold adhesive, which creates a stronger join and a more uniform finish.
A two-layer torch-on system typically lasts longer than traditional felt, with a realistic life expectancy of fifteen to twenty years when properly installed. The material is thicker and more resistant to foot traffic, which matters if you ever need to get onto the roof to clear a gutter or check a flashing.
The trade-off is cost. Torch-on is more expensive than basic felt, though it is still usually cheaper than EPDM rubber. It also requires a competent installer. A poorly torched joint is worse than a cold-bonded one because the damage can be harder to spot until it lets water in. Ask to see examples of previous torch-on work if you are considering this option.
EPDM (ethylene propylene diene monomer) rubber is a single-ply membrane that has become one of the most popular flat roof systems for domestic properties in recent years. It comes in large sheets, which means fewer joints and fewer places for water to find a way through.
EPDM is highly flexible, which means it handles thermal movement well. It does not crack in cold weather the way felt can, and it resists UV exposure without the blistering you see on older felt roofs. Manufacturers typically rate the material itself for over twenty years of service life.
The main consideration with EPDM is the upfront cost. It sits above torch-on felt in terms of installation price, particularly on smaller roofs where the material savings from fewer joints are less pronounced. However, when you factor in the reduced likelihood of maintenance calls and early failure, many homeowners find the higher initial spend worthwhile over a ten-year horizon.
EPDM is also worth considering where the roof has a complicated shape or several penetrations such as pipes or vents, because the membrane can be dressed into awkward details more reliably than felt.
Before agreeing to any flat roof system, it is worth asking your roofer a few specific questions:
Standing water that remains on the roof more than 48 hours after rain is a clear sign of a drainage problem. This is not always caused by a failed covering; a blocked outlet or an insufficient fall can cause pooling even on a roof that has not yet started to leak. Left untreated, standing water accelerates the breakdown of felt and can work its way into any small weakness.
Blistering or bubbling on a felt surface means air or moisture is trapped beneath the covering. Once a blister forms, the bond between layers is broken in that area, and cold weather can cause it to crack open. Blisters do not seal themselves.
Damp patches on the ceiling below a flat roof are an obvious sign, but the leak entry point is rarely directly above the visible damp. Water travels along rafters and decking before it finds a way through, so a thorough inspection is needed to find the true source rather than just patching the most obvious wet patch.
A proper flat roof survey looks at more than just the surface covering. Outlets and drainage points need to be clear and set low enough to draw water away from the centre of the roof. Perimeter edges need to be dressed correctly so wind-driven rain cannot get behind the covering at the fascia line. Wall junctions and upstands where the roof meets a vertical surface are a common place for failures because the seal has to flex with thermal movement year after year.
If there is any doubt about the condition of the deck beneath the existing covering, a survey may involve lifting a small area to check the timber. This is not always necessary, but it avoids an unpleasant surprise once the stripping-out starts.
We carry out flat roofing work in Bury St Edmunds and travel to nearby towns and villages including Thetford, Brandon, Elmswell, and surrounding communities. If you are not sure whether we cover your area, call us and ask.
To arrange a flat roof survey and get straightforward advice on the best option for your property, contact a local roofer and ask whether they offer a free survey appointment.
No obligation · We usually respond within 2 hours
Storm damage, active leak, damaged ridge - we aim to be on-site within 24 hours.
