Ponding After Rain
Water still sitting on the roof two days after it stopped raining means the falls have gone. That pond will find a weakness eventually.
Flat Roofing In Bagshot
Flat Roofing In Bagshot
Flat roofs fail at their edges and their outlets, almost never in the middle. Get the falls and the detailing right and a modern flat roof will outlast the extension underneath it.
Why They Leak
Standing Water Is The Enemy, Not Flatness
A flat roof is not supposed to be flat. It should carry a deliberate fall, usually around 1:80, so that every drop of water that lands on it is moving towards an outlet within seconds. Get that right and the covering spends its life damp rather than submerged.
What we find on older Bagshot extensions and garages is the opposite. The roof was laid level, or the falls have been lost as the deck sagged, and water now collects in a shallow pond in the middle. It sits there for days. Every freeze expands it, every dry spell bakes the covering underneath, and any weakness in a lap or an upstand gets found eventually.
The second failure point is the edges. Where a flat roof meets a wall, a door threshold, a rooflight kerb or a fascia, the covering has to be turned up, dressed and terminated properly. On a great many of the roofs we re-cover, that junction has been finished with a bead of mastic and nothing else — and mastic has a working life measured in a few years, not decades.
So a flat roof job worth paying for is mostly about what happens beneath and around the covering. The sheet itself is the easy part.
Warning Signs
When A Flat Roof Needs Attention
Flat roofs give plenty of notice before they fail properly. These are the signals worth acting on.
Blisters & Bubbles
Raised areas in old felt mean moisture is trapped between layers. Each hot day expands it further and stretches the covering.
Splits At The Laps
Old pour-and-roll felt goes brittle and cracks along its joints. Once one lap opens, water is inside the build-up rather than on top of it.
Lifted Edges Or Trims
A drip edge that has come away lets wind under the covering. On an exposed Bagshot plot that can peel a garage roof in a single gale.
A Springy Deck
If the roof gives underfoot, the boards beneath have taken on water. No covering laid over soft decking will last.
Blocked Outlets
Pine needles and moss silt up flat roof outlets quickly here, and a blocked outlet turns a well-designed fall into a paddling pool.
How We Do It
Building A Flat Roof That Lasts
The order matters. Skipping any of these is how a flat roof ends up being done twice.
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Strip & Assess
The old covering comes off so we can see the deck. Anything soft, delaminated or rotten is replaced rather than covered over.
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Build The Falls
Firrings or tapered insulation create a positive fall to the outlet. This is the step most commonly skipped, and the reason most flat roofs fail early.
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Lay The System
GRP, EPDM, single ply or torch-on felt, bonded or mechanically fixed as the system requires and the exposure demands.
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Detail The Edges
Upstands dressed, metal trims fitted, outlets and kerbs terminated properly. This is where the hours go, and where the roof earns its lifespan.
Flat Roof Leaking Or Ponding?
Send us a photo of the roof and the pooling and we can usually tell you whether it needs a repair or a re-cover before we visit.
Where We Work
Flat Roofs We Cover
From a small porch canopy to a full commercial roof, the same principles apply throughout.
- Rear and side extensions, including those with lanterns or rooflights
- Dormer roofs and dormer cheeks
- Detached and integral garage roofs
- Porches, canopies and bay tops
- Balconies and walk-on terraces
- Outbuildings, garden rooms and workshops
- Commercial and light industrial flat roofs
- Warm roof upgrades where insulation is being improved
Why Us
Flat Roofing Done Properly
Most of the flat roofs we replace in Bagshot failed for reasons that had nothing to do with the covering chosen.
- Falls designed and built in, never assumed to already exist
- Soft decking replaced before anything is laid over it
- Metal trims and dressed upstands instead of mastic
- Outlets sized and sited so the roof actually drains
- System chosen to suit the roof, not whatever we buy cheapest
Common Questions
Flat Roofing Questions
What people ask us before committing to a flat roof re-cover.
Cannot see your question? We are always happy to talk it through — there is no such thing as a silly question when it comes to your roof.
How long does a flat roof last?
A properly installed modern system on a sound, correctly falling deck should give you decades rather than years, and the manufacturers back that with product guarantees. The variable is almost never the material — it is whether the deck, falls and detailing beneath it were done correctly.
Which flat roof system is best?
There is no single answer, which is why we specify per roof. Walked-on balconies suit GRP, simple garages suit EPDM, larger or awkward roofs suit single ply, and outbuildings are well served by torch-on felt. Size, access, use and whether the roof will be seen all feed into it.
Can you just patch my flat roof?
Sometimes, and if a patch is genuinely the right answer we will say so. But if the covering has reached the point of blistering and splitting across its area, patching one spot simply moves the leak. We will show you photographs and let you decide with the facts in front of you.
What is the difference between a warm and cold flat roof?
A warm roof puts the insulation above the deck, keeping the structure at room temperature and largely removing condensation risk. A cold roof insulates between the joists and needs a ventilated void. Warm roof build-ups are what we recommend on most re-covers now.
Can you fit a rooflight or lantern while re-covering?
Yes, and doing both together is far cheaper than adding one later. The kerb needs building and detailing into the covering, which is straightforward while the roof is open and disruptive once it is finished.
Do you do flat roofs on conservatories?
We do, including converting tired polycarbonate conservatory roofs to solid, insulated roofs. It transforms how usable the room is in both summer and winter, and it is one of the more satisfying jobs we take on.
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