Flat Roof Repair & Replacement in Derby

There is no single best system, only the right one for your particular roof, budget and how it is used. EPDM rubber suits larger, simpler extension and garage roofs and is laid cold on most domestic decks; GRP fibreglass gives a hard, walkable shell that suits dormers, balconies and roofs with several upstands; modern reinforced-bitumen felt remains a sound, economical choice for a plain garage or outbuilding. We set out the trade-offs at the free survey so the choice fits your roof rather than our preference.

As general trade guidance rather than a guaranteed figure, a well-laid EPDM or GRP covering commonly gives twenty to thirty years, while a modern multi-layer felt system typically runs shorter than that by grade. The real determinant is not just the membrane but the deck, the falls and the ventilation beneath it, which is why we look at the whole build-up rather than only the top surface. A covering laid over a sound, correctly-falling deck to BS 6229 lasts its full life; one rolled over a tired deck does not.

Standing water, known as ponding, points to falls that were never quite steep enough or a deck that has since sagged, and while a small amount of ponding is not always urgent, persistent pools shorten the life of any covering. On EPDM and GRP the membrane tolerates it better than old felt does, but the proper fix is to correct the falls so water runs to the outlet rather than sitting until it evaporates. We assess the falls at survey and set out whether a re-lay with corrected falls is worthwhile.

A warm deck places the insulation above the structural deck with a vapour control layer beneath it, which keeps the deck warm and is the current recommended way to avoid interstitial condensation. A cold deck places insulation between the joists below the deck and must be ventilated correctly to BS 6229 and BS 5250 to stay dry. When we re-cover a flat roof we look at which build-up you have and whether it is performing, because getting this wrong is what makes a roof 'leak' when it is actually condensing.

A flat roof that keeps marking the ceiling after repair is often not leaking from above at all but condensing from within, especially where a cold-deck build-up traps warm, moist air against the underside of a poorly-ventilated deck. Repeated surface patches never fix that because the water is coming from inside the room, not through the covering. We check the covering, insulation, vapour control and ventilation together so the real cause is addressed rather than the same wet patch chased season after season.

It depends on how far the felt has gone and whether the deck below is still sound. Where blistering or a split is confined to one area and the deck is dry and solid, a well-scoped repair can genuinely extend the roof's life for a useful stretch. Where the felt has hardened, cracked and failed across the whole roof, patching one seam simply moves the next leak along, and a full re-cover is the honest answer. The survey tells you plainly which situation your roof is in.

Where a long-standing leak has softened or rotted the timber boards beneath the membrane, yes — the affected deck is replaced and the falls corrected before any new covering goes on. Laying a fresh EPDM, GRP or felt membrane over a rotten deck simply buries the problem and the roof fails again from below. We check the deck's condition during the survey and include any board replacement in the written quote so there are no surprises once the old covering is stripped.

On most domestic extension and garage decks, yes — EPDM rubber is a single sheet laid cold with adhesives rather than a torch, which suits work close to fascias, timber and neighbouring walls. That cold application is one of the reasons it is a popular choice for the rear-extension roofs behind Derby's suburban semis. GRP is also a cold, resin-applied system, while some felt grades are cold-applied and others torch-applied; we set out the method for your roof at survey.

A typical single-garage or extension flat roof is usually a one-to-two-day job for EPDM or felt, while GRP can run a little longer because the resin needs time to cure between coats and will not go down in the wet. A larger or more complex roof, or one that needs the deck replaced first, takes longer, and we give you a realistic timescale in the written quote. Weather matters more on flat roofs than on tiling, since neither resin nor adhesive behaves in heavy rain.

Yes — where the survey shows water is not reaching the outlet because the falls are too shallow or the deck has sagged, a re-cover is the natural point to build in correct falls using tapered insulation or firrings so water runs off properly. Getting the falls right is as important as the covering itself, because even the best membrane struggles under permanent standing water. We set out any falls correction in the quote so you can see exactly what is being put right.