Flat Roofs
Durable flat roof systems for extensions, garages and commercial buildings.
Overview
Flat roofs don't fail because "flat roofs just leak" — that's a reputation earned by decades of felt roofs installed with barely any fall, so water sat on them until it found a way through. A flat roof built with the correct fall for drainage, on a sound deck, with a modern membrane system, is a genuinely durable, low-maintenance option for extensions, garages, dormers and commercial units.
We install and repair flat roofs using EPDM rubber membrane and GRP fibreglass systems, both of which resist UV degradation and cracking far better than old-style bitumen felt. Where the deck itself has failed — usually from years of standing water finding its way through a worn membrane — we strip back to the joists, rebuild with new timber and OSB decking, and only then install the new covering, because a new membrane over a rotten deck just buys you a few extra months before the same problem comes back.
Correct falls, properly detailed upstands and trims, and drainage that actually goes somewhere are what separate a flat roof that lasts 20+ years from one that's back on our schedule within two winters.
What's included
- GRP fibreglass and EPDM rubber membrane systems
- Correctly engineered falls to prevent ponding
- Full deck strip-back and timber rebuild where needed
- Upstands, trims and edge detailing done properly
- Suitable for extensions, garages, dormers and commercial roofs
- Solar panel and rooflight compatible installations
Flat Roofs — recent work
A selection of jobs we've carried out for this service.
Signs it might be time
A few things that often mean it's worth thinking about flat roofs — before a small issue becomes a much bigger one.
Water visibly pooling on the roof more than 48 hours after rain
Bubbling, cracking or blistering on the membrane surface
Leaks appearing specifically at the junction between the flat roof and a wall
A soft or spongy feel underfoot when walking the roof (deck failure)
Daylight or damp staining visible on the ceiling directly beneath
A membrane that's visibly beyond its expected service life
What happens, step by step
No mystery about what happens next, who's coming, or what it costs before anyone starts work.
- 01
Inspect & measure falls
We check the existing structure, measure the falls (or lack of them), and identify whether the problem is the membrane, the deck, or both.
- 02
Recommend a system
EPDM, GRP or a repair to the existing covering — we'll recommend what suits the size, use and budget of the roof rather than a one-size-fits-all answer.
- 03
Strip back the old covering
The failed membrane comes off completely so we can see the true condition of what's underneath before quoting further work.
- 04
Rebuild the deck if needed
Rotten timber and OSB are replaced and the falls corrected, because a new membrane over a bad deck is a repair that won't last.
- 05
Install membrane & trims
The new covering is fitted with properly detailed upstands, edge trims and any penetrations (vents, pipes, rooflights) sealed correctly.
- 06
Test drainage
We check water actually clears from the roof rather than sitting on it, before calling the job finished.
Flat Roofs — frequently asked questions
The questions we're asked most about this specific service. Anything else, just call us.
EPDM, GRP or felt — what's actually the difference?
EPDM is a single rubber sheet with very few seams, flexible and long-lasting. GRP fibreglass forms a rigid, fully bonded surface with no seams at all. Both comfortably outlast traditional bitumen felt, which is why we don't fit felt on new work. We'll recommend whichever suits your specific roof.
How long does a flat roof membrane actually last?
Properly installed EPDM or GRP typically lasts 25-plus years with minimal maintenance, compared to 10–15 years for felt — and that's before accounting for felt's tendency to fail early if the falls aren't right.
Can you fix a small leak without replacing the whole roof?
Often yes, if the deck underneath is sound and the membrane failure is localised. We'll always tell you honestly if a patch repair is genuinely viable or if it's just delaying an inevitable full replacement.
Can a flat roof take the weight of solar panels?
In most cases, yes, with the right mounting system and a structural check beforehand. Let us know if solar is part of the plan and we'll factor it into the install.
Other services we offer
Most jobs touch more than one part of the roofline — here's everything else we cover.
New Roofs
Full roof installations and replacements using quality materials, fitted by experienced roofers.
Typically 2 – 5 daysDetails
Roof Repairs
Fast, reliable repairs for leaks, slipped tiles, storm damage and everything in between.
Most repairs completed in a dayDetails
Fascias & Soffits
Low-maintenance uPVC fascias, soffits and bargeboards that protect your roofline.
Typically 1 – 2 daysDetails
Guttering
New gutter installations, repairs and clearances that keep water away from your walls.
Most jobs completed in a dayDetails
Drone Roof Surveys
High-resolution drone inspections that spot problems without anyone on a ladder.
Usually completed within the hourDetails
Plastering
Interior and exterior plastering, from ceiling repairs to full re-skims.
Typically 1 – 3 daysDetailsFind out what your roof actually needs.
A thorough inspection, a photo report you keep, and an honest answer — including “it can wait” when that is the truth.