When a flat roof in Wendling starts leaking or showing its age, the most important question to answer early is whether a repair will genuinely fix the problem or whether replacement is the better use of your money.
Most flat roofs on domestic extensions and garages were built with built-up felt - layers of bitumen-impregnated felt bonded together and finished with stone chippings. Installed from the 1960s onwards, this system can last 15 to 20 years under reasonable conditions, though many are replaced earlier due to poor original workmanship or ongoing maintenance neglect.
More recent flat roofs tend to use either torch-on felt (a heavier, reinforced version applied with a gas torch) or EPDM rubber membrane, which is a single sheet of vulcanised rubber bonded or mechanically fixed to the deck. EPDM in particular has become popular on extensions and garage roofs because of its flexibility and ability to handle the temperature movement that flat roofs experience through the seasons.
Knowing what system is already on your roof helps to decide what to do next. Some systems can be overlaid under certain conditions. Others need stripping back completely before anything new goes down.
A repair is the right choice when the problem is genuinely isolated and the rest of the roof is in serviceable condition. Flat roofs fail in specific places first - usually at upstands where the membrane meets a wall, around outlets and drains, at drip edges, and at any penetrations through the surface such as soil pipes or rooflights. These are the points where the detailing is most complex and where movement and weathering concentrate.
If a roof is otherwise sound and the failure is at one of these detail points, a targeted repair carried out properly can give the roof several more useful years. The repair needs to use compatible materials - patching an EPDM roof with torch-on felt, for example, will not bond correctly and is unlikely to hold long-term. The right approach is to use the same system or a specialist repair product designed for that membrane type.
Repairs are also sensible when the roof is relatively young - say under ten years old - and the failure appears to be a workmanship issue from the original installation rather than general deterioration. A roof that was poorly detailed at an upstand from new can be fixed at that point without needing a full replacement.
Replacement becomes the right answer when the roof membrane has reached the end of its serviceable life and is failing in multiple places, when the deck beneath has deteriorated, or when repairs are being repeated without lasting effect.
A common situation is a roof where the visible surface looks passable but the deck boards beneath are wet, soft or rotten because moisture has been getting in slowly over time. Laying a new membrane over a compromised deck is a false economy - the deck needs replacing first, and once you are at that stage the full cost of a replacement is usually more sensible than a patch repair that cannot be properly bonded to a sound substrate.
Another signal that replacement is warranted is when the roof has no proper fall. Old flat roofs were sometimes laid with insufficient slope, leading to persistent standing water. Over time this ponding accelerates the breakdown of any membrane and promotes moss and algae growth that further traps moisture. A replacement at that stage offers the chance to correct the fall using tapered insulation, which also improves thermal performance.
As a rough guide, if more than a third of the surface area shows cracking, splitting, blistering or delamination, replacement is likely to be more cost-effective than repair within any reasonable timeframe.
The starting point is always a proper inspection - not just a look at the surface from the ground or from a ladder, but a hands-on check of the membrane, the upstands, the outlets and, where possible, the deck beneath. Felt roofs that sound hollow underfoot when walked on often have delaminated or moisture-laden layers that will not bond to anything new.
Questions worth asking when a contractor inspects and quotes for either repair or replacement include:
Flat roof repairs vary considerably depending on the nature and location of the problem. A straightforward upstand repair or outlet reseating might cost £150 to £400. A repair involving a section of membrane that has split or lifted, including cutting back to sound material and patching correctly, can run to £300 to £800 depending on the area involved.
Full replacement, including stripping the old material and disposing of it, inspecting and replacing any damaged deck boards, and fitting a new EPDM or torch-on felt system, typically costs £80 to £120 per square metre for a standard domestic job in this area. A single-garage roof of around 15 square metres might therefore cost £1,200 to £1,800 in total. A larger extension roof of 25 to 30 square metres would typically fall in the £2,000 to £3,600 range, depending on access, detailing complexity and deck condition.
These figures assume a straightforward job with reasonable access. A rotten deck requiring full replacement, difficult access or complex flashings around rooflights will add to the cost. Always get a written quote that breaks out the main elements so you can see what you are comparing.
Leaving a flat roof that is already leaking or showing advanced wear tends to cost more in the end. Water that gets through a failed membrane sits on the deck boards and eventually rots them. It then penetrates into the ceiling and wall structure of the room below. What starts as a roofing problem becomes a joinery, plastering and decorating problem. The longer a damaged flat roof is left, the more expensive the total repair bill becomes.
If you are uncertain whether the roof needs a repair or a replacement, the practical answer is to get it looked at properly rather than waiting to see how it develops over the winter.
Dereham Roofers works across Wendling and the surrounding villages. If your flat roof is giving you concern - whether it is actively leaking or just showing signs of age - give us a call and we will come and assess it properly. We will tell you honestly whether a repair will do the job or whether replacement is the more sensible option, and give you a clear written price for whichever route we recommend.
No obligation · We usually respond within 2 hours
Storm damage, active leak, damaged ridge - we aim to be on-site within 24 hours.
