Leaking flat roof on your extension or garage? We install modern GRP fibreglass and EPDM rubber systems that last 25+ years — no more repeated patch repairs on failing felt.
Flat roofing in Reading costs £800-£6,000 depending on size and system. We fit EPDM rubber and GRP fibreglass — both lasting 30-50 years — not short-life felt. Ideal for garages and extensions across Woodley, Earley and the estate suburbs. Free survey. Call 0118 327 2383.
Flat roofs on rear extensions, side returns, garages and outbuildings are common across Reading's housing stock. When original felt systems fail — typically after 15–20 years — we replace them with GRP or EPDM systems designed to last a generation.
GRP (fibreglass) is the preferred choice for most residential flat roofs in Reading. It forms a seamless, hard-wearing surface with no joints to fail, handles foot traffic well, and is compatible with rooflight upstands and outlet details. A well-installed GRP system carries a 25-year guarantee and needs virtually no maintenance. Most Reading extension flat roofs are good candidates for GRP.
EPDM rubber is better suited to roofs with complex geometry, very large surface areas, or where movement in the substrate is a concern. It's a single-ply membrane with excellent UV and weathering resistance, and installs quickly on large garage roofs. Both systems significantly outperform traditional built-up felt.
Flat-roofed garages are particularly prevalent across Woodley and Lower Earley's 1970s–80s estates, and across the 1960s stock in Whitley and Southcote. If your garage roof has been patched more than once in the past decade, replacement with a modern system will prove more cost-effective long-term.
“Rear extension flat roof had been leaking for two winters. Previous repair hadn't held. Reading Roofing stripped it back to the deck, found the real problem, and installed a GRP system. Bone dry since — should have done it years ago.”
Sue T. · Woodley RG5
★★★★★
“Garage roof on our 1970s semi in Earley had been patched four times. Finally replaced the whole thing with EPDM. They did it in a day, cleared everything away, and the price was fair. Very happy.”
Phil K. · Lower Earley RG6
★★★★★
“Had a GRP flat roof installed on our kitchen extension. Neat finish, clean upstands around the rooflight, and they explained the maintenance — basically nothing for 25 years. Professional job.”
A flat roof in Reading costs £800-£2,000 for a garage and £1,500-£3,500 for an extension in EPDM or GRP. See our full Reading flat roof cost guide for the EPDM-versus-GRP comparison.
Adding light to a loft, landing or flat-roofed extension often means a roof window alongside the roofing work. We also carry out Velux and skylight installation in Reading.
Honest advice
Do You Actually Need Flat Roofing?
A failing flat roof shows as pooling water, blisters, splits or damp appearing in the room below — most common on the ageing felt garages and extensions across Reading's estates.
Ponding water that sits for days after rain
Blisters, cracks or splits in the membrane
Damp or staining on the ceiling of a room below a flat roof
A felt roof over 15-20 years old
Lifting or failed edge trims and flashings
When it is not the answer: If the deck is sound and the membrane is only locally damaged, a repair or overlay is the sensible fix — a full strip is oversell where the timber beneath is dry. Read the full guide.
We assess the membrane and, crucially, the deck condition beneath — the hidden variable that decides overlay versus full strip.
2. Written quote with system options
You get EPDM and GRP options with an honest recommendation for your roof shape and use.
3. Scheduling
We book the work — most garage and extension roofs are done in 1-2 days.
4. Strip or overlay & install
We fit the new membrane, integrate upstands and flashings, and correct any falls so water drains properly.
5. Cleanup & guarantee
Site cleared, with a 20-year manufacturer guarantee on the membrane plus our workmanship guarantee.
Timescales
Typical Timescales
Job
Typical duration
Single garage (EPDM)
1 day
Extension roof (GRP)
1-2 days
Larger/complex flat roof
2-4 days
Deck replacement (added)
0.5-1 day
Converted garage warm-deck
2-3 days
GRP needs dry, mild conditions to cure — we schedule fibreglass work around the weather to avoid a compromised finish.
Access
Access, Scaffolding & Permits in Reading
Most flat roofs are single-storey — ladder or tower access — so scaffold is rarely needed unless the roof abuts a second storey. Scaffold is specified for: flat roofs abutting a second storey, or where edge protection is required for a larger area - always itemised in your written quote, never a hidden extra, and we arrange it.
Reading's mix of Victorian terraces in Newtown and Katesgrove and post-war estate housing in Whitley and Lower Earley means access varies from tight terraced frontages to open estate driveways. Pavement scaffold and skip permits go through Reading Borough Council; allow a few working days on streets like Newtown terraces off the Oxford Road, the narrow streets of Katesgrove where space is tight.
Pricing
What Flat Roofing Costs in Reading
Job
Typical range
Notes
Single garage (EPDM)
£800-£1,600
Rubber, single sheet
Single garage (GRP fibreglass)
£1,000-£2,000
Seamless laminate
Extension roof (EPDM)
£1,500-£3,000
Depending on size
Extension roof (GRP)
£1,800-£3,500
Complex geometry
Large / complex flat roof
£3,000-£6,000
Multiple drainage points
Converted garage warm-deck (GRP + insulation)
£2,000-£4,000
Habitable-room spec
What moves the price
Roof size in square metres
System chosen (EPDM vs GRP)
Deck condition — reuse or replace
Number of upstands, drains and penetrations
Insulation requirement (heated space below)
Worked example: A failing felt garage roof on a 1970s Lower Earley property, deck sound, replaced in EPDM with new trims: around £1,150 including waste removal.
No deposit for garage and small extension roofs. Staged payment on larger jobs when materials arrive. All prices include VAT.
Guarantee
What the 10-Year Guarantee Actually Covers
The membrane carries a 20-year manufacturer guarantee; our workmanship on the installation is covered for 10 years in writing.
Covered: workmanship for 10 years, in writing, transferable if you sell.
On top: manufacturer warranties on materials (terms vary by product).
Not covered: storm or impact damage - that is an insurance matter, and we will document it for your claim.
If a fault appears in covered work, we come back and put it right. No quibbling, no re-charge.
Low-level work with minimal disruption — some fumes during GRP curing, so we keep the area ventilated and clear. You do not need to stay home for external work - we just need power and access agreed in advance.
EPDM can be laid in most conditions; GRP needs dry weather to cure properly, so we weather-plan fibreglass jobs. Thames Valley damp is well within both systems’ range once cured. Thames Valley humidity and the Kennet and Thames river corridors slow drying and accelerate moss, especially on north-facing slopes.
A typical 3m x 4m rear extension flat roof in Reading costs £1,400–£2,200 for GRP replacement including removal of the existing felt. A standard single garage roof (5m x 6m) typically runs £1,800–£2,800. Larger or more complex roofs are priced on survey. We provide free quotes.
A correctly installed GRP system carries a manufacturer-backed 25-year guarantee and realistically lasts 40–50 years with minimal maintenance. This compares to 15–20 years for traditional mineral-cap felt and makes GRP the most cost-effective choice for most Reading homeowners.
It depends on the system age and condition. Felt roofs within 5–8 years of installation and with isolated damage can often be repaired. Felt roofs older than 15–20 years, or those with widespread blistering, cracking or multiple failure points, are typically better replaced — further repairs on an aged system rarely hold long-term.
Yes. We regularly install and replace rooflights as part of flat roof projects. We work with Velux and FAKRO fixed rooflights, and can specify GRP upstands to suit your chosen unit. Rooflights significantly improve natural light in kitchen and rear extension spaces.
If the membrane is sound and the failure is localised — a lifted edge, a single split — repair is usually right. If the membrane is more than 15 years old on a felt system and showing surface cracking or blistering across multiple areas, replacement gives better long-term value. We assess flat roofs across Reading for free and give you a straight answer.
GRP fibreglass is a rigid laminated system that cures to a seamless hard shell — ideal for complex shapes. EPDM rubber is a flexible bonded membrane better suited to large open areas with thermal movement. Both significantly outlast traditional felt. We specify based on your roof geometry.
Like-for-like flat roof replacement does not normally require building regulations approval. If the replacement significantly changes thermal performance, a completion certificate may be required under Part L. New flat roof extensions always need full building regulations compliance. We flag any requirements at survey stage.
Areas Covered
We Cover All of Reading
Based in Reading, we serve the whole borough and surrounding Berkshire towns. Call 0118 327 2383 to confirm coverage.
The flat roofing stock across Reading's post-war estate suburbs — Woodley, Earley, Whitley, Southcote and the surrounding areas — represents the largest single maintenance challenge in the Reading catchment. Tens of thousands of flat-roofed garages and kitchen extensions were built between 1960 and 1990 on built-up felt systems with a design life of 10 to 20 years. Many of this stock has never been replaced and is significantly past its design life.
Our flat roofing survey assesses deck condition before any specification is agreed. A flat roof that is leaking because the membrane has failed but the OSB or plywood deck beneath is sound can be overlaid with a new EPDM or GRP system without full deck replacement. A deck that has been repeatedly wetted through a failing membrane may have deteriorated to the point where replacement is necessary — and discovering this after a new membrane is laid is expensive. We assess and advise honestly before a price is agreed.
For straightforward rectangular flat roofs — the standard garage or extension configuration across Woodley, Earley and Whitley — EPDM rubber is our standard recommendation. For complex shapes with multiple drainage outlets, upstands, or penetrations — common on rear kitchen extensions with soil pipe penetrations — GRP fibreglass is the better specification. We set out the reasons for our recommendation in writing.
Why Felt Replacement Is Not the Answer
We are regularly asked to repair or re-felt flat roofs that have already been repaired or re-felted once or twice. The issue is not the quality of the previous repair — it is that felt is not the right material for a flat roof that needs to last. Felt systems have a design life of 10 to 20 years. Every 15 years you are paying for the same job again. Over the 40-year life of a typical Reading garage, a felt system costs two to three times what a single EPDM or GRP replacement would have cost upfront.
We no longer install felt on new flat roof work. Every flat roof replacement we carry out uses either EPDM rubber or GRP fibreglass, both of which carry manufacturer guarantees of 20 years and realistic service lives of 30 to 50 years. The price premium over felt is recovered in the first maintenance cycle you avoid.
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No call-out fees. No obligation. A straight answer from a local Reading roofer.
