Information verified and published: 21 October 2026
What a new flat roof or a flat roof repair costs in London depends on material, roof size, access and condition. This guide is based on real Knights Roofing projects completed across London in 2025–2026 — and if your roof only needs fixing, the repair section below explains what's involved.
Please note: prices shown are from — every project is quoted individually based on size, access and condition. Book a free survey for an exact price.
Whether you're replacing an old felt roof, considering EPDM rubber, or exploring GRP fibreglass, several factors shape what you'll actually pay. If you only need a fix rather than a new roof, jump to flat roof repair — most localised damage doesn't need a full replacement.
EPDM, GRP, felt and PVC have different price points and lifespans
Larger roofs benefit from economies of scale
Central London commands 20–30% premium pricing
Difficult access increases labour costs
Deck board replacement adds to total cost
Material choice affects both price and lifespan — a free survey gives you an exact price for your roof.
Lifespan: 40–50 years
Best for most residential projects · very low maintenance
Lifespan: 30–40 years
Ideal for balconies and complex shapes · low maintenance
Lifespan: 15–20 years
Budget projects and temporary solutions · moderate maintenance
Lifespan: 25–35 years
Commercial buildings · low maintenance
Felt has the lowest upfront cost but the shortest lifespan, while EPDM costs more initially but lasts roughly twice as long — often working out better value over time. Book a free survey and we'll recommend the option with the best lifetime value for your roof.
Not every leaking flat roof needs replacing. Knights Roofing are flat roof specialists based in Battersea, repairing EPDM, GRP and felt roofs across Clapham, Chelsea, Putney, Wimbledon, Wandsworth, Richmond and surrounding areas since 2003. Our flat roofers diagnose the problem on a free survey and fix it the same day where possible.
From a single leak to storm damage, we'll tell you honestly whether a repair will last — and only recommend replacement when it's the better value.
Book a free repair survey
Most flat roof problems are localised and can be fixed with a repair. A free survey gives you a straight answer, but here's how to tell:
Not sure which applies to you? Our flat roofers will give you an honest recommendation on a free survey — we never push unnecessary work. Book your free survey.
GRP adds multiple resin coats plus a colour topcoat and anti-slip finish.
Felt uses two or three torch-on layers depending on the specification.
EPDM is either fully adhered or mechanically fastened, depending on the roof.
Beyond the core installation, these are the most common extras — flagged upfront in a proper quote rather than added later.
These are quoted individually as part of your survey, alongside the core installation. Planning permission is rarely required for flat roof replacement — it typically counts as repair and maintenance. Listed buildings and conservation areas may have restrictions. Building Regulations compliance under Approved Document L applies to most projects; we handle this as part of the job.
Traditional felt flat roofing remains popular across Southwest and West London for its affordability and proven performance. Here's how we handle the most common felt roof repairs.
Standing water can lead to leaks, structural damage and premature deterioration. Proper drainage is essential to prevent costly repairs.
Air or moisture trapped beneath the membrane can cause bubbles, weakening the roof and increasing the risk of leaks.
Shifts in the building structure or ageing materials can cause the membrane to wrinkle, reducing effectiveness and durability.
Cracking patterns resembling alligator skin come from prolonged sun exposure and age — a sign replacement may be due.
Poor drainage and accumulated debris lead to plant growth, which holds moisture and accelerates degradation.
Temperature changes cause expansion and contraction, leading to cracks, weakened seams and potential leaks.
Dealing with a leak right now? Our guide to flat roof leak causes and fixes explains what you can safely check yourself before we arrive.
At Knights Roofing, we provide written quotations within 2–3 working days of inspection, clearly detailing costs, materials and timelines. Request your free inspection.
If your property also needs attention to its guttering, fascias or roof drainage, our team can assess this during the same survey.
A trusted flat roofing company serving Southwest and West London since 2003 — direct access to our flat roofers, not a call centre. See our full South West and West London coverage area.
It depends on the material and roof size — flat roof replacement starts from £1,499, with EPDM rubber roofing from £1,999. Material, access, structural condition and insulation requirements all affect the final price. Book a free survey for an exact, itemised quote.
Traditional torch-on felt has the lowest upfront cost, but only lasts 15–20 years compared to EPDM's 40–50 years — so it typically needs replacing again within the roof's lifetime, while EPDM's higher upfront cost is a one-off. Over the life of the roof, EPDM usually works out better value despite costing more initially.
EPDM rubber roofing starts from £1,999. Other materials and sizes are quoted individually after a free survey — this assumes existing deck boards are in good condition, as insulation upgrades, structural repairs or scaffolding add to the total.
Yes, typically 30–40% less over a comparable project. Both perform well; GRP is generally preferred for roofs that double as balconies, while EPDM offers better value for standard flat roofs.
Usually not — it's normally covered by permitted development rights. Exceptions: listed properties, conservation areas with added restrictions, significant changes to roof height or structure, or new rooflights overlooking neighbouring properties. You will still need to comply with Building Regulations, which we handle as part of the job.
Small garage (15–20m²): 1–2 days. Standard extension (25–35m²): 2–3 days. Large extension (40–60m²): 3–5 days. Commercial (80m²+): 5–10 days. This assumes good weather and no major structural surprises.
Current Building Regulations require improved thermal performance when replacing a flat roof, so insulation is typically recommended and often required for compliance. Always confirm in your quote whether it's included and to what specification.
Usually covered: storm damage, fire, accidental damage, vandalism. Usually not covered: wear and tear, age-related deterioration, lack of maintenance, or pre-existing problems. Document the damage with photographs and notify your insurer before starting work — most policies require multiple quotes.
EPDM rubber: 40–50 years. GRP fibreglass: 30–40 years. Single-ply PVC: 25–35 years. Traditional felt: 15–20 years. Proper installation and regular maintenance help roofs reach the top of these ranges.
Most quotations include VAT at the standard 20% rate. Reduced VAT (5%) may apply if the building has been empty for 2+ years and is being renovated, you're converting a non-residential building to residential use, or the work is for a registered charity. Standard occupied residential replacements are charged at 20%.
Mainly labour costs, access challenges (parking restrictions, congestion, limited space), higher demand for skilled roofers, and stricter enforcement of Building Regulations and party wall requirements. Central London (Zones 1–2) sits at the top of the range, with costs easing in outer London.
Flat roof repair starts from £199. The exact cost depends on the extent of damage, roof access, and the material involved. We provide a free inspection and a transparent, itemised quote before starting any work — every repair is priced individually.
A repair fixes localised damage such as leaks, tears or failing seams, and is appropriate when damage affects less than about 30% of the roof and the structure is sound. Replacement means stripping the old roof and installing a new one. A professional repair typically extends a roof's life by 5–10 years.
Frequent leaks, visible cracks, ponding water, or ageing signs like blistering and alligatoring all point to a problem — but only an inspection shows whether a repair will hold. Our flat roofers give you an honest recommendation on a free survey.
Yes. We provide same-day emergency flat roof repairs across Southwest and West London, 7 days a week, typically responding within 1–2 hours for urgent leaks. We can make the roof watertight within hours, with permanent repairs scheduled at your convenience. Call 020 7126 8439.
All types — felt (torch-on and traditional), EPDM rubber, GRP fibreglass, single-ply membranes and asphalt. Whether it's a house extension, garage, commercial building or balcony, we use the right materials and methods for that system.
All of Southwest and West London, including Battersea (our base), Clapham, Chelsea, Putney, Wimbledon, Richmond, Wandsworth, Fulham and surrounding areas.
Keep drainage clear, schedule inspections at least twice a year, and fix small issues early before water reaches the deck. Regular maintenance is far cheaper than repairing water damage later.
All of this is specific to flat roofs. If your property has a sloped roof instead, costs and repair methods differ significantly — see our guide to pitched roof repairs in London for slate, tile and clay roofs. And if you're planning further roof works, we can also advise on chimney repointing if your stack shows signs of deteriorating mortar.
Repair or replacement — written, itemised quote within 2–3 working days. Same-day emergency repairs available. No obligation.
Get your free quote Call 020 7126 8439Please note: prices shown throughout this page are from — every project is quoted individually based on size, access and condition.