Most flat roof repairs we see in Swanley are on older felt roofs — three-layer bituminous felt that was the standard for decades. The problem is that felt has a limited lifespan, and the joints between sheets are always the weak point. They crack, separate, and let water in. We can patch them, but if the felt is generally past its best, we'll tell you — because there's no point spending money on a repair that'll only last another year or two.
Flat roof repairs cover a wide range of work depending on the type of covering and what's gone wrong. On felt roofs — still the most common type we see across Swanley — typical repairs include patching splits and cracks with new felt or liquid applied waterproofing, re-bonding lifted sections, replacing failed upstands where the roof meets a wall, and clearing blocked outlets that cause water to back up. On EPDM rubber roofs, repairs usually involve patching punctures with EPDM offcuts and adhesive, or re-bonding edges that have lifted. GRP fibreglass roofs occasionally need topcoat renewal or repair of cracks caused by poor original installation. We also repair single-ply PVC and TPO membranes, re-welding seams and patching damaged areas. Before we repair anything, we assess whether the repair will actually last. There's no point patching a 25-year-old felt roof that's perishing all over — you'd just be shifting the leak to a different spot. For properties in Swanley, where a suburban town in north-west Kent with predominantly post-war housing estates and 1960s-70s developments now reaching the stage where roof renewal is essential, many flat roof sections are reaching the age where they need either significant repair or full replacement. We'll always check the condition of the deck underneath (looking for rot in chipboard or OSB) and the state of the insulation, because these affect whether a repair is worthwhile. Our approach is honest — if a repair will hold and give you good life, we'll do it. If the covering or deck is too far gone, we'll recommend replacing with a modern EPDM or GRP system that'll last decades.
Bituminous felt gets brittle with age, especially the top capsheet that takes the brunt of UV and weather exposure. Cracks form along stress lines, at joints between sheets, and around the edges where the felt meets trims or upstands. Once the top layer splits, water tracks between the felt layers and spreads across the deck. We see this constantly on 15-20 year old felt roofs across Kent.
Blisters form when moisture trapped between felt layers or between the felt and the deck heats up in summer and expands, pushing the top layer into a bubble. Small blisters are cosmetic, but large ones weaken the felt and eventually crack open, letting water in. They're a sign that moisture is present in the roof build-up, which needs addressing.
If water sits in puddles on your flat roof for more than 48 hours after rain, the falls are inadequate. Ponding puts extra weight on the structure, accelerates degradation of any covering, and provides a constant source of water that will exploit the smallest weakness. When repairing or replacing a flat roof, building in proper falls is essential.
Where a flat roof meets a wall or parapet, the upstand detail is critical. On felt roofs, the upstand often fails first — the felt cracks or the mortar fillet behind it crumbles, allowing water to track down behind the covering. Lead or GRP upstand details are much more durable than felt and mortar, and we often upgrade these during a repair.
Flat roof repairs in Swanley vary widely depending on what's needed. A simple felt patch over a split or crack typically costs £200-£500. Re-bonding a lifted section of felt or EPDM runs £150-£400. Replacing a failed upstand where the roof meets a wall is usually £300-£600. If the whole covering needs an overlay — laying a new membrane over the existing surface — expect £800-£1,500 for a typical garage or small extension. Full replacement with a new EPDM or GRP system, including stripping the old covering and replacing the deck if needed, ranges from £1,500-£4,000 depending on size and system choice. Emergency temporary repairs using liquid rubber or self-adhesive flashing tape are £100-£250 as a stop-gap until a permanent fix can be done.
For felt repairs, we use Chesterfelt or IKO torch-on capsheet — a much heavier and more durable grade than the old pour-and-roll felt. Liquid waterproofing for emergency patches is Cromar Pro GRP or Evercryl — these brush on and cure to form a flexible waterproof coating. For EPDM patch repairs, we use the same Firestone or ClassicBond membrane as the original installation, bonded with the manufacturer's adhesive. We keep rolls of Tyvek breathable membrane for situations where the underlying felt needs replacing. Where deck boards have rotted, we replace with 18mm OSB3 Sterling Board. Edge trims and drip details are Freefoam or Manthorpe extruded aluminium.
We inspect your flat roof in Swanley to identify exactly what's gone wrong — where the water is getting in, what type of covering you've got, and what condition the deck and structure are in. We check inside too if there's a ceiling below.
Based on the condition of the covering and the structure beneath, we'll tell you whether a repair will hold or whether replacement is the smarter investment. We explain our reasoning and give you options with clear pricing for each.
Whether it's a targeted patch, an upstand replacement, an overlay, or a full system replacement, we work efficiently and cleanly. We protect the surrounding area and work around the weather — flat roofing materials need dry conditions to perform properly.
After the repair, we check from below for any signs of residual water ingress. We clear debris from the roof surface and gutters, ensure water flows towards the outlets, and talk you through what we've done. Written guarantee on all repair work.
Flat roofs are a fixture on properties across Swanley — rear extensions built in the 1960s-80s, garage roofs, bay window tops, and dormer cheeks. Swanley is a suburban town in north-west Kent with predominantly post-war housing estates and 1960s-70s developments now reaching the stage where roof renewal is essential. The majority of these flat sections were originally covered in three-layer bituminous felt, which has a lifespan of 10-15 years. Many have been patched and re-covered at least once. The South East's mix of wet winters and increasingly warm summers creates a punishing cycle for flat roof coverings — cold-weather cracking followed by summer heat that softens and blisters the felt. Properties near trees have the added problem of leaf debris blocking outlets, causing ponding that accelerates deterioration.
Felt, EPDM, GRP, single-ply — we repair and replace every type of flat roof covering found across Kent. Whatever's on your roof, we know how to fix it.
We'll tell you honestly whether your flat roof is worth repairing or whether it needs replacing. We'd rather you spent your money wisely than paid for a repair that fails in six months.
When a repair is the right call, we do it properly — with the right materials for your specific covering, not a generic sealant bodge. A good repair can add years of life to a flat roof.
When replacement is needed, we install EPDM and GRP — systems that last 30-50 years. No more replacing your flat roof every 10-15 years.
A patch repair on a felt roof typically costs £200-£500. Upstand repairs run £300-£600. An overlay of the whole roof is £800-£1,500. Full replacement with EPDM or GRP — if the covering is past saving — is £1,500-£4,000 depending on the size. We'll always give you a clear price after the inspection and explain why we're recommending the approach we are.
As a general rule: if the damage is localised, the rest of the covering is in decent condition, and the deck underneath is sound, repair makes sense. If the covering is failing all over, there's widespread ponding, or the deck has rotted, replacement is the better investment. We check all of these factors and give you an honest recommendation. Nobody benefits from a repair that fails in six months.
Recurring leaks usually mean the covering has reached the end of its life and patches aren't going to solve the underlying problem. Felt roofs typically last 10-15 years, and once the material starts to perish, fixing one spot just moves the problem to the next weakest point. If your flat roof keeps leaking despite repairs, it's probably time for a full replacement with a modern system.
Yes, though the weather conditions on the specific day matter. Felt and EPDM can be worked in colder temperatures, but everything needs to be dry — we can't bond materials to a wet deck. GRP fibreglass needs temperatures above 5°C to cure. We monitor the forecast and schedule accordingly. For emergency repairs, we can usually find a dry window even in winter.
Blisters form when moisture gets trapped between felt layers or between the felt and the deck. When the sun heats the roof, that moisture turns to vapour and pushes the felt up into a bubble. Small blisters are usually harmless, but large ones weaken the felt and can eventually split open. They're a sign that moisture is present in the roof build-up, which ideally needs addressing.
Traditional three-layer felt: 10-15 years. Torch-on felt: 15-20 years. EPDM rubber: 50+ years. GRP fibreglass: 25-30 years (with topcoat refresh extending to 40-50). The huge difference in lifespan is why we recommend EPDM or GRP when a flat roof needs replacing — the upfront cost is higher, but you're paying for one roof instead of three or four over the same period.
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