Flat roofing across Cambridgeshire and Norfolk

Most flat roof problems we get called out to are the same story: an old felt roof laid years ago that has finally given up, or a newer roof laid too fast without the falls and upstands done properly, leaving water sitting where it should be running away. Flat roofing done right is not complicated, but it has to be done in the right order with the right material for the job.

GRP or EPDM

The two materials we fit most are GRP fibreglass and EPDM rubber, and the honest answer for your roof depends on the size, shape and how many upstands or penetrations it has.

• GRP fibreglass is laid in liquid form and cures into a single seamless surface, strong underfoot, good on roofs with a lot of detailing like rooflights or complex upstands, and usually lasts 25 to 30 years
• EPDM rubber comes in large sheets with very few joints, flexes with the building through temperature changes so it resists cracking, and suits simpler shaped roofs particularly well

Both carry a manufacturer-backed material guarantee of up to 25 years when we install them, on top of our own 10 year written workmanship guarantee covering the fitting.

Ventilation matters as much as the membrane

A flat roof deck that cannot breathe properly traps moisture underneath the covering, which condenses on the underside of the deck and can rot it from below even while the top surface stays perfectly watertight. Cold roof and warm roof constructions each handle this differently, and getting the ventilation or insulation build-up wrong is a common reason a flat roof deck fails years before the membrane on top of it does. We check this as part of every flat roof inspection, not just the visible surface.

What happens on installation day

The existing covering is stripped back to the deck, the deck is inspected and any damage repaired before anything new goes down, since covering a compromised deck simply hides the problem rather than fixing it. The new membrane is then laid, dressed into every upstand and penetration, and finished with edge trims. We check the whole roof for fall and drainage once complete, before we consider the job done.

Most single storey flat roofs, garages, extensions and dormers, are completed within one to two days, weather permitting, and we agree that timeframe with you in writing before the job starts, so you know what to expect.

Insulation while the deck is open

Because the roof has to be opened up to fit a new membrane anyway, it is usually the most cost effective point to improve the insulation above the deck at the same time, particularly on an older garage or extension where the original build had little or none. We will raise this at the inspection where it is genuinely worth doing rather than add it as an unnecessary upsell.

Why flat roofs actually fail

It is almost never the material itself. It is fall, drainage and detailing. A flat roof needs a slight fall built in so water runs off toward a drain or gutter rather than pooling, and every upstand, edge trim and pipe penetration needs to be sealed properly, not just dressed and hoped for. We see roofs laid by others fail within two or three years because the fall was never built in at all.

Repair or full replacement

A flat roof with a small blister, a split at one seam or a failed upstand can often be repaired. See our flat roof repair page. Once the membrane has failed across a wide area or the deck underneath has rotted from years of standing water, replacement is the honest recommendation, and we will show you why with photographs rather than just say so.

Getting the fall right the first time

The single most important decision on any flat roof job is the fall, the slight slope built into the deck that directs water toward an outlet rather than letting it sit. Too little fall and water pools after every rainfall, accelerating wear on the membrane and adding weight the structure was not designed to carry indefinitely. We set this out before the deck is finished, using firring pieces or tapered insulation where the existing structure needs correcting, rather than laying a new membrane over an old, flat problem.

What we cover

Garages, extensions, dormers, porch canopies and full commercial flat roofs across Wisbech, King's Lynn, Norwich, Cambridge and Peterborough, plus the rest of Cambridgeshire, Norfolk, west Suffolk and south Lincolnshire. For larger commercial work, see commercial and industrial roofing. For the detail on each material, see GRP fibreglass roofing and EPDM rubber roofing.