Flat Roof Repair & Installation in London
City Building and Roofing Ltd are flat roof specialists in London and Surrey. GRP, EPDM, felt systems — all with written guarantees. 25-year GRP guarantee. Free quotes — call 01932 950 995.
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Flat roofing is used on extensions, garages, dormers, commercial buildings and low-pitch roof areas. City Building and Roofing Ltd install and repair felt, GRP fibreglass and EPDM rubber flat roof systems across London and Surrey, with written guarantees and free quotations.
City Building and Roofing Ltd are flat roof specialists serving London and Surrey. We install and repair all types of flat roofing systems — including GRP fibreglass, EPDM rubber membrane, three-layer felt and torch-on felt — for residential and commercial clients throughout London and the South East.
All flat roof installations come with generous written guarantees. Our GRP flat roofs carry a 25-year guarantee and all new flat roofs carry a minimum 10-year insurance-backed guarantee — valid even in the unlikely event our company ceases to trade. We also carry £5,000,000 public liability insurance.
Whether you have a flat roof on an extension, a garage, a commercial property or a converted loft — our team of City & Guilds qualified tradesmen will specify and install the right system for your property. Call us on 020 7118 0095 for a free, no-obligation quote.
Flat Roof Systems We Install
GRP Fibreglass Flat Roofing
25-year guaranteeGRP is our most popular flat roof system. It creates a seamless, watertight surface with no joins — extremely durable and available with a 25-year guarantee. Ideal for extensions, garages and larger flat roof areas.
EPDM Rubber Flat Roofing
20-year guaranteeEPDM is a synthetic rubber membrane that is lightweight, flexible and highly resistant to UV degradation. It is an excellent choice for roofs that experience significant thermal movement.
Three-Layer Felt System
10-year guaranteeThe three-layer felt system uses a vapour control layer, reinforced underlay and fire-rated mineral cap sheet to create a durable, cost-effective flat roof. Popular for commercial properties and larger domestic roofs.
Torch-On Felt
Written guaranteeTorch-on felt uses heat to bond layers together, creating a strong, weather-resistant membrane. A reliable and cost-effective flat roofing option for smaller areas.
Choosing the Right Flat Roof System
Each flat roofing system has its strengths, and the right choice depends on the roof's size, use and detailing. For a seamless finish with the longest guarantee, see our dedicated GRP fibreglass roofing page. For garages, extensions and roofs with significant thermal movement, EPDM rubber roofing is often the best fit. Roofs with complex details, plant or restricted access frequently suit liquid roofing and waterproofing, applied cold with no hot works.
If your existing flat roof is tired but the deck beneath is sound, a flat roof overlay system can re-cover it without a full strip-up — less disruption and less waste. And if the roof is actively leaking right now, start with our roof leak repairs service and we will find and fix the source before recommending anything further.
Flat Roof Repair Services
- Flat roof leak investigation and repair — we find the source and fix it permanently
- Blister and crack repairs on GRP, felt and EPDM roofs
- Flat roof resealing and refurbishment — extending the life of existing roofs
- Ponding water issues — drainage improvement and falls correction
- Perimeter detail repairs — upstands, abutments and edge trims
- Emergency flat roof repair — fast response across London and Surrey
Why Choose City Building and Roofing?
- Flat roof specialists — all systems installed by City & Guilds qualified tradesmen
- 25-year guarantee on GRP, minimum 10-year IBG on all new flat roofs
- £5,000,000 public liability insurance
- Hundreds of flat roofs installed for residential and commercial clients across London
- Free, expert advice on which system is right for your property
- Flat roofing services throughout London and the South East
- Family-owned business — established over 10 years with a strong local reputation
Free Flat Roof Quote in London or Surrey
Not sure which flat roof system is right for your property? Call us for expert advice and a free, no-obligation written quote. We cover all of London and Surrey.
Common Problems We Fix
Ponding water
Water that sits on a flat roof accelerates wear and finds any weakness. We correct falls and outlets so the roof drains properly.
Splits and cracks
Older felt and tired membranes crack as they age and move, letting water through. We patch or re-cover depending on condition.
Blistering
Trapped moisture and heat cause blisters that eventually burst. We cut out and make good, or recommend a new system if it is widespread.
Failed laps and seams
The joints between sheets are the most common leak point on felt and EPDM. We reseal or replace the affected sections.
End-of-life felt
Mineral felt has a limited lifespan. Once it is brittle and shedding granules, a re-cover in GRP or EPDM is more cost-effective than repeated patching.
Poor drainage
Blocked or badly positioned outlets cause water to back up. We clear and reposition drainage as part of the works.
How Our Process Works
Inspection and survey
We assess the existing roof, the falls and the condition of the deck beneath.
System recommendation
We advise the best system — felt, GRP or EPDM — for your roof, how it is used and your budget.
Written quote
A clear, itemised quote, free and without obligation.
Installation
We prepare the deck and install the chosen system to manufacturer specification.
Guarantee
A manufacturer warranty plus our workmanship guarantee, with insurance-backed cover on eligible installations.
How Much Does It Cost?
Flat roof costs depend on the size and shape of the roof, the system chosen — felt, GRP fibreglass or EPDM rubber — the condition of the deck below and access. A small garage roof is at the lower end; a large or multi-level flat roof with deck repairs costs more.
- The area and complexity of the roof
- The system chosen — felt, GRP or EPDM
- Condition of the timber deck beneath
- Access and whether edge protection is needed
- Extras such as new outlets, trims or insulation
City Building and Roofing Ltd provide free written quotes before any work begins, across London and Surrey.
Get a Free Quote
Find City Building and Roofing Ltd on Google
Customers across London and Surrey can find City Building and Roofing Ltd on Google to read reviews, view recent work and contact the team directly. We recommend calling the correct local number for your area — Surrey enquiries on 01932 950 995 and London enquiries on 020 7118 0095.
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Areas We Cover
Frequently Asked Questions
What is the best flat roof system in the UK?
There is no single best system — it depends on the roof. GRP fibreglass gives a seamless, hard-wearing finish ideal for balconies and extensions; EPDM rubber is flexible and long-lasting; modern torch-on felt is a cost-effective choice. We recommend the right system for your roof, budget and how it is used.
Is GRP better than felt roofing?
GRP fibreglass is generally more durable and longer-lasting than traditional felt, with a seamless finish and no laps to fail, though it costs more upfront. Felt remains a reliable, budget-friendly option when installed well. For roofs that need to last, GRP is often the better long-term value.
Is EPDM better than felt?
EPDM rubber is a single-sheet membrane that is very flexible and resistant to UV and temperature changes, often lasting decades. It usually outperforms standard felt on lifespan, especially on larger roofs where fewer joints mean fewer weak points. Felt can still be the right choice for smaller or budget projects.
How long does a GRP roof last?
A correctly installed GRP fibreglass flat roof should last 25 years or more, and our GRP system is backed by a 25-year manufacturer warranty plus our workmanship guarantee. Lifespan depends on correct installation, adequate falls and the roof not being subjected to heavy foot traffic.
Why is my flat roof leaking?
Flat roofs most often leak through splits, blisters and failed laps in the membrane, or through tired flashing and upstands. Ponding water and blocked outlets make these failures worse. We trace the actual failure point and either repair it or re-cover the roof, depending on its overall condition.
Can a flat roof be repaired or does it need replacing?
Many flat roofs can be repaired if the membrane is generally sound and the problem is localised. Once the covering is brittle, widely blistered or shedding granules, repeated patching is false economy and a re-cover is more cost-effective. We give you an honest assessment either way.
How much does flat roof repair cost?
It depends on the size of the failure, the system and access. A small patch repair is inexpensive; a full re-cover of a large or multi-level roof costs more. We provide a free written quote setting out the work and the price before anything starts.
What are the signs a flat roof is failing?
Look for ponding water that never drains, splits, cracks and blisters in the surface, lifting or open laps, damp patches on the ceiling below, and granules collecting in the gutter. Any of these suggests the covering is nearing the end of its life and should be inspected.
Ready to Get Started?
Contact us today for a free, no-obligation quote. We serve all of London and Surrey with professional roofing and building services.
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