Flat Roofing
Flat roofing that survives a Channel winter
Flat roofs have a bad reputation earned entirely by cheap ones. A properly specified flat roof is one of the most reliable things on a building. The trouble is that the difference is invisible on the day it is finished and obvious eight years later.
They fail at the edges
Almost no flat roof fails in the middle. It fails at the perimeter, the upstands and the abutments — the places where wind gets under an edge and starts to lift, and where water meets a vertical surface. On the coast the uplift forces at those edges are the whole design problem. A fully bonded membrane with mechanically fixed edge trims is a fundamentally different proposition to a loose-laid sheet with a bit of adhesive round the outside.
Choosing the system
EPDM rubber is a single sheet with no seams on most domestic roofs, stays flexible in cold weather and copes well with movement. GRP fibreglass cures into one continuous surface and gives a hard, walkable finish that suits balconies and dormer tops. High-performance torch-on felt is still an excellent system when it is a proper multi-layer build-up rather than one layer over old. We will tell you which suits your roof, the access and the budget — and why.
Falls and ponding
"Flat" is a figure of speech. Every flat roof needs a fall so water leaves it, and a great many older ones do not have enough, which is why they sit under standing water for weeks. Where the existing deck has no usable fall we build one in with tapered insulation rather than laying a new membrane over a puddle and hoping.
UV, and why coastal flat roofs age faster
Reflected light off water means more ultraviolet than the same roof would get inland, and UV is what makes old felt go brittle, blister and split. Modern membranes are far more resistant to it, but detailing still matters — a well-chosen system badly detailed will fail before a modest system detailed properly.
What the job includes
- EPDM rubber, GRP fibreglass and high-performance felt systems
- Existing decks inspected and replaced where they have gone soft
- Tapered insulation to build in a proper fall where there is none
- Fully bonded membranes with mechanically fixed edge trims
- Upstands, kerbs and abutments detailed for coastal wind uplift
- Insulation upgrades to current standards during a re-cover
- Rooflights, outlets and rainwater connections formed in
Talk it through first
Half the time we can tell you on the phone whether it sounds like a morning’s work or something bigger.
Flat Roofing
Questions we get asked about this
How long should a flat roof last?
A properly installed modern membrane on a sound, well-drained deck should give you decades rather than years. We will not put a specific number on it here, because the honest answer depends on the system, the fall, the exposure and whether anyone ever walks on it — and the number quoted in an advert is rarely the one that materialises.
Can you go over the existing flat roof?
Sometimes, if the deck below is genuinely dry and sound. Far more often the deck has been quietly wet for years under a failed membrane, and overlaying it seals the problem in. We open it up and look before we tell you either way.
Is a rubber roof better than fibreglass?
Neither is better in the abstract. EPDM handles movement and cold well and goes down as a single sheet; GRP gives a harder, walkable surface and takes complex shapes and trims neatly. The right answer depends on your roof, not on which one a company prefers to fit.
Can I walk on it or use it as a balcony?
Only if it has been built for it. A standard flat roof is designed to be walked on for maintenance, not used as a terrace. If you want a usable space, say so at the survey and we will specify a system and a build-up that will take it.
Free quotes & advice
Get a free quote for flat roofing
We will come out, look at it properly and put it in writing — what is wrong, what we propose, and what we are using. No charge either way.