Garages, extensions, bay tops and porches across Tonbridge and Sevenoaks. Felt, EPDM rubber or GRP fibreglass, with the honest cost-per-year maths for each.
Blisters, failed seams and small splits in felt or EPDM, sealed properly.
£150 – £450Three-layer torch-on felt. 15 to 20 years of life. Single garage around 18m².
£1,400 – £2,200One-piece membrane, no seams to fail. 30 to 50 years. The best cost per year for most homes.
£90 – £140 per m²Hard, walkable, smart finish. 25 to 30 years. The right choice for balconies and terraces.
£110 – £160 per m²Prices reviewed July 2026. Ranges assume straightforward access on a domestic property in West Kent. Deck repairs, where needed, are agreed at a rate before work starts.
Send a photo of the roof and the stain. We will tell you whether it is a £200 patch or a roof at the end of its life.
Send us a photoFelt is the cheapest way to cover a flat roof and still the right answer when budget rules or the roof is due for replacement anyway when an extension gets built. Its weakness is lifespan: 15 to 20 years, less if water pools.
EPDM rubber costs more per square metre but goes down as a single sheet with no seams, which removes the way most flat roofs actually fail. At 30 to 50 years of life, a £2,000 EPDM garage roof costs roughly £50 a year against £90 or more for felt. That is why it is what we recommend for most garages and extensions.
GRP fibreglass cures into a hard shell you can walk on, looks the smartest of the three, and suits balconies or anywhere with foot traffic. It needs dry weather and good workmanship to lay well, which is reflected in the price.
Most failed flat roofs we see did not wear out, they drowned. Water that cannot reach the outlet sits in a pool, finds the smallest defect and works at it all winter. A proper replacement corrects the falls with firring strips so the new roof drains, which is why it outlasts the roof it replaced.
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A single garage of around 18 square metres runs £1,400 to £2,200 in felt. EPDM rubber costs £90 to £140 per square metre and GRP fibreglass £110 to £160 per square metre, so the same garage lands roughly £1,600 to £2,900 in those materials. Patch repairs are £150 to £450. Prices reviewed July 2026.
Felt is cheapest up front and lasts 15 to 20 years. EPDM rubber costs a little more and lasts 30 to 50 years, which makes it the best cost per year for most garages and extensions. GRP fibreglass gives a hard, walkable finish lasting 25 to 30 years and suits balconies and roofs that get foot traffic.
If it is one blister or one failed seam on a roof under ten years old, yes. If the felt is past 15 years and pooling water, a repair buys you a season or two at best. We will tell you which case yours is rather than selling you the bigger job by default.
A garage roof is typically one to two days including stripping the old covering. Larger extension roofs run two to three days. EPDM and GRP need dry weather to bond properly, so booking moves with the forecast.
Only where they need it. The deck gets inspected once the old covering is off, sound boards stay, rotten ones are replaced and charged at the rate agreed in the quote before work starts.
Yes. Standing water usually means the falls are wrong or the deck has sagged. A replacement is the chance to correct the falls with firring strips so water actually reaches the outlet, which is half the reason the new roof outlasts the old one.
Pooling water that sits for days, blisters or bubbles in the surface, cracked or lifting seams, green growth, and damp patches on the ceiling below. Any of these is worth a photo and an enquiry before winter makes it worse.