Newmarket Roofers helps homeowners in Soham decide whether to repair a failing flat roof or replace it outright - and carries out both types of work on extensions, garages, and outbuildings.
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When a flat roof starts letting in water, the instinctive response is to get it patched. Sometimes a patch is exactly the right answer. Other times, patching an old roof is money spent on borrowed time - the underlying membrane has failed across a wider area, and the next leak is only a few months away. Knowing which situation you are in before spending anything is the key decision.
We carry out flat roof work across Soham and neighbouring towns including Newmarket and Bury St Edmunds, fitting and repairing felt and EPDM rubber systems on extensions, garage roofs, outbuildings, and bay tops. The repair-versus-replace question comes up on almost every call-out, so here is a straightforward way to think through it.
A repair is the right choice when the failure is genuinely localised. A single split or blister in an otherwise sound membrane, a failed upstand at one corner, or a gap that has opened where flashing meets a wall - these are containable problems on a roof that still has useful life left in it.
The useful indicators for a repair-viable roof are:
A competent roofer will check the deck by walking it carefully and pressing at different points. Soft or spongy areas mean moisture has got into the decking boards or insulation below, and that changes the calculation significantly.
An older felt roof that has been patched two or three times is rarely worth patching again. Mineral felt degrades from UV exposure and thermal movement - it expands in summer heat and contracts in winter cold, and over years this opens fine cracks across the whole surface, not just at one point. By the time it is obviously leaking, the membrane is often brittle and porous across most of its area.
Replacement becomes the clearer choice when:
Replacing a flat roof on a typical single-storey extension or garage of 15-20 square metres costs approximately £1,500 to £3,500, depending on the system and the condition of the existing deck. An EPDM rubber replacement sits toward the higher end of that range but typically outlasts a felt replacement by many years. A repair on a localised failure might cost £200 to £600 depending on access and the extent of the work. If you are spending towards the top of that repair range on a roof that is already fifteen years old, the numbers often favour replacement.
This point deserves its own section because it changes the cost of both options. Flat roof decks in domestic construction are usually 18 mm or 22 mm tongue-and-groove OSB or plywood. When a membrane fails and water sits on the deck, it eventually saturates the board and then the joists below. Saturated decking loses its structural integrity and must be replaced before any new covering is installed.
If only a small area of deck is damaged, that section can be cut out and replaced as part of a repair. If the saturation is widespread, the cost of replacing the deck shifts the economics firmly toward full replacement. A roofer who quotes for a patch without checking the deck condition is missing a crucial step - the patch may hold, but the soft deck beneath it will compress and crack the new material within a short time.
On some roofs where the original felt is in moderate condition but past its best, an overlay - fitting a new membrane directly over the existing felt without stripping it off - is possible. This is less disruptive and less expensive than full strip and replacement. It is only appropriate when the existing deck is dry and firm, the existing felt is reasonably flat (no major ridging or blistering), and the roof's load capacity can accommodate the additional weight.
Overlaying is not a long-term solution on a poor-quality deck or where water has already got beneath the existing membrane. In those cases, stripping back to the joists and starting properly is the only approach worth paying for.
When replacement is the verdict, the material choice matters. Traditional torch-on felt is familiar and widely used. A properly installed two-layer system lasts twelve to twenty years. EPDM rubber is a single-piece membrane bonded to the deck, with no seams across the main field of the roof, and it is significantly more resistant to UV degradation and thermal cycling. It is the material of choice where longevity is the priority.
Both systems need the same careful attention to edge details, upstands, and drainage falls to work properly. The membrane itself is only as good as the installation around it.
A good roofer should be able to explain their repair-versus-replace recommendation clearly. Ask them:
A contractor who recommends replacement on a six-year-old roof without a clear reason for it, or who recommends a patch on a twenty-year-old felt roof that is leaking in three places, deserves to be questioned. The honest answer is not always the most profitable one for the roofer, so a clear explanation of the reasoning is a reasonable thing to expect.
If you have a flat roof in Soham that is causing concern, call us to arrange an inspection. We will check the membrane, the deck, the drainage, and the edge details, and give you a straight answer on whether repair or replacement makes more sense - with the costs for both set out clearly before you decide anything.
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Call any time. Calls are answered day and night and passed straight to our roofers.
