Flat Roof Repairs & Replacement in Stockport & East Cheshire

Most flat roof installations in Stockport fall between £100 and £200 per square metre, supplied and fitted. A typical 30 m² domestic garage roof works out at roughly £3,000 – £6,000 depending on the system. Reinforced felt sits at the lower end (£80 – £120 per m²), EPDM rubber in the mid-range (£100 – £160 per m²), and GRP fibreglass at the upper end (£120 – £200 per m²). Final price depends on the size of the roof, the condition of the deck underneath, the system chosen, and access. We provide a written quote at survey, no verbal estimates.

A modern EPDM rubber roof, installed correctly, has a realistic service life of 50 years or more. GRP fibreglass lasts 25–30 years, and the reinforced torch-on felt systems used today typically give 15–20 years before needing replacement. These are all a world apart from the single-layer pour-and-roll felt used on houses built in the 1970s and 80s, which often failed within 10 years. Lifespan is determined as much by the quality of the install as by the material itself, correctly detailed upstands, properly bonded laps, and a clean deck beneath the membrane are what the manufacturer's warranty assumes.

EPDM is a factory-made sheet of synthetic rubber laid as a single piece, virtually no seams, very flexible, and extremely long-lived on large flat areas. GRP is laminated in place on site with fibreglass matting and resin, seamless, rock-hard, and walkable, which makes it the right choice for balconies, complex upstands, and smaller roofs with lots of detailing. EPDM wins on lifespan and simplicity; GRP wins on foot traffic, detailing, and surface hardness. Neither is strictly "better". They suit different buildings. We'll recommend whichever is right for your roof rather than whichever is in the van.

Ponding happens when the roof deck has insufficient fall, flat roofs need a minimum 1:80 slope to drain reliably, or when the deck has sagged over time because of rotten boarding underneath the membrane. Water that sits on the surface for more than 48 hours accelerates every failure mode at once: UV breakdown, blistering, and membrane fatigue. Correcting ponding usually means tapered firing strips installed over the deck before the new membrane goes down, creating the subtle slope the original roof lacked. In more serious cases, the deck itself needs partial or full replacement.

Replacing more than 25% of the roof's area triggers Building Regulations Part L, which sets minimum U-values for the thermal performance of the roof. For a like-for-like repair under that threshold, approval isn't required. For a full replacement, we include the necessary insulation and provide the written documentation Building Control needs at sign-off. This is handled as part of the job. You won't need to liaise with the council yourself, and we don't treat it as an extra charge line on the quote.

Almost always, it needs to come off. Overlaying traps moisture between the old membrane and the new one, hides problems with the deck below, and leaves you with a roof that's heavier than the original structure was designed to carry. The only situation where overlaying is defensible is a single-sheet EPDM installation over a sound, dry existing membrane with no blistering or ponding, and in practice, a roof old enough to be replaced rarely meets those conditions. Stripping back to the deck costs a little more but produces a roof you can trust for decades, not years.

For a full replacement of an extension, a garage used as living space, or any habitable-area roof, yes, Building Regulations Part L requires it and we include it as standard. For outbuildings and uninsulated garages used for storage only, insulation isn't mandatory. That said, the cost uplift for rigid board insulation is modest compared to the long-term energy savings and the comfort difference in the room below, and we recommend it in almost every case.

EPDM can be installed across the full range of British temperatures provided the deck is dry and the adhesive is within its working window. We install EPDM roofs all year round. GRP is more weather-sensitive: the resin needs a minimum temperature and dry conditions to cure correctly, so we'll sometimes schedule GRP jobs for a drier forecast or switch to EPDM for a time-critical winter replacement. Felt systems sit between the two. We'll tell you honestly what the weather limits are for your specification rather than agreeing to a start date we can't realistically hit.

The majority of flat roof leaks originate at upstands, abutments, and edge flashings rather than in the middle of the membrane. Common causes include upstands laid to the wrong height, lead flashings not chased into brickwork courses, laps that weren't fully bonded during installation, or flashings that have split because of thermal movement. These aren't material failures, they're detailing failures. Getting the edges right is what separates a roof that lasts 30 years from a roof that leaks in 5, and it's where we spend disproportionate time on every install.

Yes, modern flat roof systems are now a better choice for most single-storey extensions than they were a generation ago. An EPDM or GRP extension roof has a realistic 25–50 year service life, meets or exceeds the insulation requirements of Part L when correctly specified, and usually costs less than a pitched tile roof over the same footprint. Pitched extensions still make sense where planning designation, conservation area rules, or architectural character demand them, but a well-built flat roof is no longer the compromise it used to be.

Yes, all new flat roof installations come with a written workmanship guarantee from us, and EPDM and GRP systems carry manufacturer material warranties on top. The workmanship guarantee covers everything related to the install itself: membrane bonding, upstand detailing, flashing integration, and the decking underneath. Material warranties cover failure of the membrane itself under normal conditions. You get both documents in writing at handover, along with any Building Regulations sign-off paperwork where applicable.