If your flat roof in Tuddenham is showing damp patches, blistering felt or pooling water, catching the problem early is the difference between a repair and a full replacement.
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Mildenhall Roofers carries out flat roof installations and repairs across Tuddenham and the surrounding villages. Flat roofs need specialist attention that a general builder rarely provides.
This page focuses on something every homeowner with a flat roof should understand: the warning signs that tell you something is wrong, and the underlying causes behind each one. Spotting the right signal early saves money and prevents interior damage that can spread well beyond the roof itself.
A flat roof should never be completely flat. A correctly installed roof carries a fall of at least 1 in 80, which is enough to drain rainwater to a gutter or outlet. If you can see standing water on the surface 48 hours after rain, the fall is insufficient or the substrate beneath has sagged and created a low spot.
Ponding accelerates deterioration of any membrane system. Felt softens and splits under the constant freeze-thaw cycle that water trapped in a dip creates. EPDM rubber handles ponding better than felt, but even rubber will eventually fail around the edges of a persistent pond if the water is pushing against a upstand or parapet detail. The root fix is to re-lay the deck with the correct fall, not simply to patch the surface.
Blisters are one of the most visible signs on a felt roof. They look like raised bubbles, sometimes as large as a hand span, sitting on the surface of the membrane. The cause is almost always moisture or air trapped between layers at the time of installation, expanding in summer heat and pressing the felt away from the substrate beneath.
A blister that is intact and dry inside is not immediately dangerous, but it is a weak point. Once it cracks - which will happen eventually as the felt ages and loses its flexibility - water gets in and the decay spreads quickly. A small crack in a blister can allow litres of water per week into the roof build-up without producing an obvious indoor drip.
The most common place for a flat roof to fail is not in the middle of the open field of felt or rubber - it is at the edges, where the membrane turns up against a wall, a parapet, a chimney or a roof light frame. These upstand details require the membrane to be dressed up a vertical surface and bonded securely. As the roof expands and contracts with temperature changes, the membrane pulls at these fixed points.
On older felt roofs, the top edge of an upstand is often finished with a separate piece of lead flashing. When that lead cracks, lifts or pulls away from its chase in the masonry, rainwater runs straight down behind the felt rather than over it. Lead flashing repairs are a separate trade skill - the flashing must be cut into the wall, not simply stuck on the surface with mastic, which will fail within a couple of seasons.
Not all flat roof leaks show up as a wet patch directly below the point of entry. Water that gets through a membrane can travel along a joist, run along a vapour barrier and emerge a metre or more away from where it came in. This makes flat roof leaks harder to trace than pitched roof leaks, where gravity tends to keep water moving in a more predictable direction.
A damp patch on an internal ceiling that appears in cold weather but not after rain is sometimes condensation rather than a leak - warm, moist air from the room below is hitting a cold surface. This points to an insulation or ventilation problem in the roof build-up rather than a membrane failure. The two issues need different fixes, so correctly identifying the source matters before any work starts.
Mineral-surfaced felt has a finite lifespan. A single-ply torch-on felt roof laid correctly will typically perform for 10 to 15 years before the mineral layer starts to erode and the felt beneath becomes brittle. Three-layer built-up felt systems last longer, often 20 years or more when installed well. But when felt reaches the end of its life, it cracks along its grain, especially where it has been repeatedly walked on or where it lies over a board joint in the deck below.
Cracks along board joints tell you the deck itself is moving. This happens when the plywood or OSB decking has absorbed moisture and begun to swell, warp or delaminate. Patching surface cracks without addressing a failing deck below is temporary at best. When a deck is compromised, the boards need to come up and be replaced before any new membrane is laid.
If you walk on a flat roof and feel soft or springy areas, the decking has likely rotted or delaminated. Plywood used for flat roof decks should be a minimum of 18mm exterior-grade board. When water has been sitting on a failing membrane for an extended period, it works through to the deck and the structural timber beneath. A soft spot that feels harmless from above can represent a joist that has lost much of its load-bearing capacity.
Never ignore a soft deck. Structurally compromised decking is a safety risk during any maintenance visit, and if it collapses under a maintenance worker or under a heavy snowfall, the repair bill grows significantly.
The most useful thing you can do when you notice any of the signs above is to document what you see before calling a roofer. Note whether the interior damp appears after rain, after a cold snap, or both. Photograph any visible surface damage and the area around gutters and outlets. This information helps a roofer diagnose the cause faster and gives you something to cross-check against any report or quote you receive.
Ask any roofer you speak to to describe specifically where they believe the water is entering, what they think is causing it, and what the proposed repair involves. A vague answer - "the felt's had it, needs re-roofing" - without a clear explanation of the deck condition, the fall, the upstand detail and the drainage is not enough to base a decision on.
We cover Tuddenham and the nearby villages of Icklingham, Herringswell, Cavenham and Worlington, as well as Mildenhall and West Row. Whether the job is a straightforward felt repair on a garage roof or a full EPDM replacement on an extension, call us to arrange a roof survey so we can give you an accurate assessment of what is needed.
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Call any time. Calls are answered day and night and passed straight to our roofers.
