What a new flat roof costs in Salisbury in 2026, comparing EPDM rubber, GRP fibreglass and felt for garages, extensions and dormers. Clear per-m² and per-job pricing.
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📞 Call Now: 0172 223 9611A flat roof in Salisbury costs £1,500–£6,000 for a typical garage or extension. Per square metre: felt £40–£70, EPDM rubber £60–£100, GRP fibreglass £80–£120. EPDM and GRP far outlast felt. Free survey and fixed quote, no call-out fee: 0172 223 9611.
Three systems dominate domestic flat roofing. Felt is cheapest upfront but shortest-lived at 15–20 years. GRP fibreglass gives a hard, seamless finish lasting 25–40 years but needs dry conditions above 5°C to cure, so winter installs often can't proceed. EPDM rubber is a single-sheet membrane with the longest life — 30–50 years — and tolerates damper conditions better, which matters in Salisbury's river-valley climate.
For most Salisbury garages and extensions we recommend EPDM or GRP over felt: the modest extra upfront cost pays back many times over in lifespan. The correct fall to the outlet and proper upstand heights matter more than the headline material — ponding water from insufficient fall is the single most common cause of premature flat-roof failure, whatever the covering.
Full replacements over a set proportion of the roof usually trigger a Building Regulations requirement to upgrade insulation, and often Building Control sign-off. We include that in our quotes rather than springing it later, and we flag deck repairs before starting wherever the old boards are likely to be soft.
Flat roofs are everywhere in Salisbury once you look: the single-storey rear extensions added to the Victorian terraces off Fisherton Street and Castle Road, the flat-roofed garages on the post-war estates at Bemerton Heath and Bishopdown, and the bay-window tops and dormers across the 1930s semis. Each fails in its own way, and each carries its own price.
The extensions and garages on the low-lying, tree-shaded parts of town — Harnham, Britford, the streets nearest the water meadows — suffer most from standing water and moss. Salisbury's five converging rivers keep humidity high on the valley floor, and a flat roof that doesn't drain cleanly stays wet, which shortens the life of felt dramatically and is exactly where switching to EPDM pays off. Blocked outlets from leaf fall make it worse, so we check and clear drainage as part of any flat-roof survey.
Bay-window and dormer roofs on the 1930s and Victorian stock are small jobs but detail-critical: the leadwork where the flat meets the wall or the pitched roof above is where leaks start, not the membrane field. A bay top in Salisbury typically runs £450–£1,200 depending on size, material and how much leadwork the junction needs — we price these individually because the detailing varies house to house.
Older felt roofs on the post-war estates are reaching the end of the line all at once. Many Bemerton Heath and Bishopdown garages and porch roofs still carry their original built-up felt, now brittle, blistered and cracking at the laps after decades of sun and frost. These are ideal EPDM conversions — a single-day strip and re-cover that replaces a roof at the end of its life with one that will outlast the house's next owner — and they are among the most common flat-roof jobs we quote across Salisbury.
Typical supplied-and-fitted prices including strip-off, new deck where needed, covering and edge trims:
GRP needs dry weather above 5°C to cure, so we schedule it into dry windows. All figures confirmed by fixed written quote after a free survey. Salisbury sits on the southern-England baseline for labour.
BS 6229, the British Standard for flat roofing, specifies a minimum fall of 1:80 to the outlet — insufficient fall causing ponding is the single most common cause of premature flat-roof failure.
— BS 6229:2018
Garage, extension or dormer roof leaking? Book a free flat-roof survey and fixed quote.
📞 Call 0172 223 9611Flat roofs fail differently to pitched ones — the signs are ponding, splits and blistering rather than slipped tiles.
When it is not the answer: If the membrane is sound and only a flashing or upstand has failed, a localised repair beats a full recover — we'll tell you which you need. Read the full guide.
We check the deck, falls, upstands and outlets, and establish whether it's a repair or a recover.
Itemised quote specifying the system — EPDM rubber, GRP fibreglass or high-performance felt — and the price.
Booked around a dry window; flat-roof systems need dry conditions to bond.
We strip the failed covering, correct the falls and insulation where needed, and lay the new membrane with dressed edges and outlets.
Site cleared, outlets tested, and the guarantee handed over.
| Job | Typical duration |
|---|---|
| Small flat roof repair | 2–4 hours |
| Garage or extension recover | 1–2 days |
| Large flat roof (EPDM/GRP) | 2–4 days |
| Warm-deck rebuild with insulation | 3–5 days |
Membranes need dry, mild conditions to bond — we won't lay in rain or hard frost.
Access is often from a tower or short scaffold depending on height and the deck. Scaffold is specified for: first-floor flat roofs, anything over a garage height, or where edge protection is required - always itemised in your written quote, never a hidden extra, and we arrange it.
Salisbury's dense Victorian terraces off Fisherton and Milford mean rear-access scaffold and permit-controlled pavement space, while the post-war Bemerton Heath and Bishopdown estates give easier access but ageing concrete-tile roofs. Pavement scaffold and skip permits go through Wiltshire Council; allow a few working days on streets like Fisherton Street, Milford Street where space is tight.
| Job | Typical range | Notes |
|---|---|---|
| Small flat roof repair | £180–£500 | Localised patch |
| Felt garage roof recover | £800–£1,600 | High-performance felt |
| EPDM rubber roof | £1,600–£4,000 | Single-ply, 20yr+ warranty |
| GRP fibreglass roof | £2,000–£5,000 | Seamless, durable |
| Warm-deck rebuild w/ insulation | £2,500–£6,000 | Meets current regs |
Worked example: An EPDM rubber recover on a typical single-garage roof in Salisbury: around £1,400 including strip and disposal.
No deposit on repairs under £500; staged payments on larger jobs with nothing up front before materials are on site. Repairs are standard-rated; a full re-roof usually attracts 5% VAT.
Covering SP1, SP2 and surrounding postcodes.
EPDM and GRP systems carry long manufacturer warranties (often 20 years+) alongside our 10-year workmanship guarantee.
If a fault appears in covered work, we come back and put it right. No quibbling, no re-charge.
Minimal inside the home — work is external, though there may be some odour from adhesives on the day, which clears quickly. You do not need to stay home for external work - we just need power and access agreed in advance.
Flat-roof work is the most weather-sensitive we do; we schedule tightly around dry spells and never leave a deck exposed. Salisbury sits where five rivers meet, so valley-floor humidity accelerates moss and slows drying, while higher ground catches wind-driven rain.
"Our extension roof off Castle Road had ponded and leaked for years. They stripped it, corrected the fall and fitted EPDM. Bone dry through the wettest winter since."
"Garage roof done in a day — EPDM, tidy job, fair price. They talked me out of felt and explained exactly why. Glad they did."
"The bay roof on our 1930s semi kept leaking where it met the wall. Turned out to be the leadwork, not the felt. They sorted the detail properly — first firm to actually diagnose it."
Most flat roofs don't fail in the middle — they fail at the edges and junctions. The perimeter upstand where the roof meets a wall, the drip trim at the eaves, and the point where a flat extension roof abuts the pitched roof above are where water finds its way in. That is why we spend as much time on trims, upstands and leadwork as on the membrane field itself, and why a cheap quote that skimps on edge detailing is a false economy on any Salisbury property.
Fall and drainage are the other half of a lasting flat roof. Salisbury's position at the meeting of five rivers keeps the valley-floor air damp, and a roof that ponds because it lacks the minimum fall to the outlet will hold that water and degrade faster. Where we replace a flat roof on a low-lying property in Harnham, Britford or near the Avon, we correct the fall as part of the job rather than simply re-covering a roof that was always going to sit wet. Blocked outlets from leaf fall compound the problem, so we make sure the drainage path is clear and, where tree cover is heavy, fit guards.
Insulation now forms part of most replacements. Where more than a quarter of a flat roof is renewed, Building Regulations generally require an insulation upgrade, and full replacements usually need Building Control sign-off. Rather than treat these as surprise extras, we include them in the quote from the outset and explain how a warm-deck build-up improves both compliance and the comfort of the room below — particularly on the single-storey rear extensions so common across Salisbury's terraced and semi stock.
Choosing between EPDM and GRP comes down to the roof. For a straightforward garage or extension where longevity is the priority, EPDM's 30–50 year life and tolerance of damp installation conditions usually wins. For a roof that will be walked on, or where a hard seamless finish and crisp trims matter, GRP is the stronger choice, provided the weather allows it to cure. We recommend based on your roof and how it's used, not on what's quickest for us to fit.
A typical garage or extension flat roof costs £1,500–£6,000 in Salisbury. Per square metre, felt runs £40–£70, EPDM rubber £60–£100, and GRP fibreglass £80–£120, supplied and fitted.
EPDM lasts longest (30–50 years) and tolerates Salisbury's damp valley climate well, making it our usual recommendation. GRP gives a harder, seamless finish (25–40 years) but needs dry weather to cure. Both far outlast felt.
These low-lying, tree-shaded areas near the water meadows stay damp because Salisbury's converging rivers keep humidity high. Standing water and moss shorten felt life dramatically, which is why we recommend EPDM there.
Like-for-like replacement usually doesn't need planning permission, but full replacements often need Building Control sign-off and an insulation upgrade under Building Regulations. We include this in our quotes.
A single garage roof is often done in a day; a medium extension takes two to four days. GRP takes longer because of curing time and needs dry conditions above 5°C.
On Salisbury's 1930s and Victorian stock, bay and dormer leaks almost always start at the leadwork where the flat meets the wall or pitched roof, not the membrane. The fix is correct lead detailing, not more sealant.
EPDM and felt can be installed in stable cool weather, but GRP fibreglass needs temperatures above 5°C and dry conditions to cure. We schedule GRP into suitable windows and can advise on timing.
Yes. Our flat roofs carry a written workmanship guarantee, and EPDM and GRP systems come with manufacturer warranties of 20 years or more when correctly installed.
Free survey, honest advice on EPDM versus GRP versus felt, and a written quote with no call-out fee. Garages, extensions, dormers and bay roofs across Salisbury.
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