Flat roofs on extensions, garages and outbuildings need the right material and a proper finish to last. We install and repair felt and EPDM rubber flat roofs across Ely and the surrounding fenland villages.
Call any time. Calls are answered day and night and passed straight to our roofers.
They are practical and cost-effective to build, but they need the right system installed correctly or they become a persistent source of leaks. We fit and repair flat roofs using high-quality felt systems and EPDM rubber, and we are honest about which option suits a given roof and budget.
The two systems we work with most are torch-on felt and EPDM rubber membrane. Each has different strengths, and the right choice depends on the roof area, how it drains, what sits below it and what the customer wants to spend.
Torch-on felt is a reinforced bitumen membrane applied in two or three layers using a gas torch to bond each layer fully. When done correctly it produces a seamless, waterproof finish that handles thermal movement well. A properly installed torch-on system typically lasts 15-20 years before replacement is needed, though this varies with exposure and how the roof drains.
Matching materials are straightforward to source, and patch repairs are possible if a localised fault develops before the end of the roof's useful life.
EPDM (ethylene propylene diene monomer) is a synthetic rubber membrane that comes in large sheets, reducing the number of joints and therefore the number of potential weak points. It bonds to the deck with contact adhesive and the edges are taken up the upstand and sealed with purpose-made tape and trim. EPDM handles temperature extremes particularly well - it stays flexible in cold weather and does not crack or blister in summer heat the way older felt can.
On a correctly prepared deck with good drainage, EPDM can last 25 years or more. It is well suited to larger flat roof areas where minimising joints is a priority, and it is straightforward to repair if a penetration or edge detail fails.
A good flat roof job starts with the deck. If the existing deck boards or plywood are soft, wet or uneven, laying a new membrane over them is a waste of money - the problems will come through within a few years. We remove the old covering, inspect the deck fully and replace any soft or damaged sections before any new material goes down.
Falls matter too. A flat roof is never truly flat - it needs a minimum fall of 1:80 (roughly 12mm per metre) to drain properly. On many older extensions the falls are inadequate, or the outlet position means water ponds away from the drain. We can introduce tapered insulation or adjust the outlet position to improve drainage as part of a replacement job. Standing water is the fastest way to shorten a flat roof's life.
Upstands - where the membrane turns up against a wall or parapet - need to be taken up at least 150mm above the roof surface and dressed properly. This is where a lot of flat roof failures start, because a poorly finished upstand lets water get behind the membrane rather than over it.
Not every flat roof problem requires a full replacement. A roof that has failed in one place - a split at a joint, a lifted edge, a cracked outlet collar - can often be repaired to extend its working life. The decision to repair or replace depends on the age of the existing covering, how much of it is in sound condition, and whether the deck beneath is intact.
A common problem on felt roofs is blistering, where air or moisture trapped between layers forces the surface up. Small blisters that have not broken can sometimes be left; a blister that has cracked and let water in needs cutting out and patching properly. Simply pressing a blister flat and coating over it with bitumen paint is not a repair - it is a delay.
For EPDM roofs, the most frequent failure points are the edge trims and any pipe or skylight penetrations. The membrane itself is tough but the adhesive bond at edges can lift if it was not applied to a clean, primed surface. Re-bonding and re-taping a lifted edge is a quick, effective repair if the membrane is otherwise sound.
Flat roof costs vary with size, system choice and deck condition. As a guide, a standard single-garage flat roof (roughly 15-20 square metres) typically costs £800-£1,500 for a torch-on felt replacement, or £1,000-£1,800 for EPDM, with deck repairs adding to both figures if needed. Extension flat roofs of 20-40 square metres run from around £1,200 to £2,500 or more depending on system and condition.
Where water has got into a lap joint or under an edge trim, it will freeze and expand, forcing the gap wider each winter until it becomes a visible failure.
If you have a flat roof on an extension or outbuilding that is causing concern, call us to arrange an inspection. We will tell you plainly what condition the roof is in, whether repair or replacement makes sense, and what the cost will be before any work starts.
No obligation · We'll call you to arrange a free visit
Call any time. Calls are answered day and night and passed straight to our roofers.
A new roof is one of the most significant investments you can make in your property. We install new roofs across Ely and
Active leaks, storm damage, slipped tiles, lifted ridge tiles and failed flashings need attention before the damage spre
When a roof reaches the end of its life, patching it up costs more in the long run than replacing it properly. We carry
Cracked tiles, leaking flashings, loose ridge tiles - roof problems rarely improve on their own. We carry out roof repai
