GRP fibreglass and EPDM rubber flat roofing for extensions, garages and outbuildings. No more leaking felt. Long-lasting seamless systems with 20-year manufacturer warranties.
Chichester’s coastal UV intensity and harbour moisture make the flat roof system specification more consequential than in inland locations. GRP fibreglass and EPDM rubber both significantly outlast traditional felt in this environment. We specify the system to the property, size and exposure conditions at the survey.
Garage Flat Roof (GRP)
£900–£1,800
Extension Flat Roof (GRP)
£1,800–£4,000
Large Area (EPDM)
£1,600–£5,500
Survey
Free
GRP Fibreglass
GRP cures to a seamless rigid surface with no joints to open. The UV-stable gelcoat provides protection that outlasts felt surface treatment by a factor of 3 to 4 in Chichester's coastal UV environment. Design life of 25 to 40 years. We back all GRP installations with a 20-year manufacturer guarantee and a 10-year workmanship guarantee.
EPDM Rubber
EPDM single-ply membrane is installed in very large sheet sizes — often a single sheet for a standard garage. Its flexibility handles building movement without cracking. Excellent UV and ozone resistance with a design life of 30 to 50 years. Preferred for large areas and any application where structural movement is anticipated.
Why Not Felt
Traditional mineral felt has a 8 to 12 year lifespan in Chichester's coastal UV environment. The upfront saving versus GRP is recovered in the first replacement cycle. Over 30 years, felt is significantly more expensive than GRP — both in direct cost and in the disruption of repeated replacement. We do not specify felt for any new flat roof installation.
Free survey — no call-out fee — Donnington & surrounding area
Post-war residential with harbour-adjacent salt air acceleration. For flat roofing in Donnington, this means nail fixings corrode earlier than inland, lead oxidation accelerated. We factor this into our survey, specification and material choice on every Donnington job — not as an afterthought but as the starting point for getting the work right.
Customer Reviews
What Donnington Customers Say
★★★★★
"Excellent garage flat roof replacement in grp. Free survey, clear quote, arrived on time and cleaned up completely. Exactly what you want."
Stanley B. · Donnington
★★★★★
"Used them for extension flat roof with epdm. Honest assessment, matched materials perfectly, no pressure on scope. Very happy with the result."
Reginald P. · Donnington
★★★★★
"Called for failed felt replaced with grp fibreglass after another contractor let me down. Professional from first call to completion. Recommend unreservedly."
Donnington sits south of chichester between the a27 and chichester harbour, combining post-war housing age with harbour-adjacent salt air acceleration. For roofing work in Donnington, this means Galvanised nail fixings corrode earlier here than on equivalent inland properties — the harbour proximity shortens the nail sickness timeline by 5 to 8 years. Residential streets between the a27 and the harbour edge. We factor all of this into our survey, specification and material choice on every Donnington job.
Donnington properties are assessed with the harbour proximity factor built into our specification from the start. Stainless fixings on guttering brackets, patination oil on lead work and enhanced durability materials on re-roofing are part of the standard Donnington specification — not extras or upgrades that need to be requested.
Free survey across all Chichester postcodes and the surrounding area. Written quote with full itemised breakdown. No call-out fee, no obligation, and no pressure to commit before you are ready. We have been carrying out this work in Chichester and the surrounding area for over 20 years. Our reputation here is built on honest assessment and correct specification — not on selling work that is not needed. Call 01243 278085 to arrange a free survey.
The flat roofing specification for properties in the Chichester coastal area needs to account for UV intensity, salt aerosol and the wind loading that differs between sheltered city centre locations and exposed peninsula sites. GRP performs well across the area when correctly installed. EPDM is preferred for larger areas and the most exposed coastal sites where installation temperature constraints make GRP more difficult to specify with confidence. We advise on the system appropriate to each property at the survey.
Honest advice
How to Tell You Need Flat Roofing
Flat roof problems in Chichester almost always come down to a failed felt covering at the end of its 8–12 year life — ponding, splits, or blistering on an extension or garage roof.
Water pooling on the roof more than 48 hours after rain
Blisters, splits or cracks in an old felt surface
A damp patch on the ceiling directly below a flat roof
Felt lifting at the edges or around the upstand
A flat roof over 10 years old that has never been replaced
When it is not the answer: If the covering is a modern GRP or EPDM system only a few years old and the failure is a single localised split, a patch repair may be all it needs — not a full replacement. Read the full guide.
Warm deck vs cold deck flat roof constructionThe process
What to Expect: Flat Roofing in Donnington
1. Free survey
We assess the deck condition, the falls, and whether the failure is localised or end-of-life across the whole roof.
2. Written itemised quote
A quote covering deck repair if needed, the chosen system, and all edge detailing and upstands — itemised.
3. Scheduling
We book dry conditions for GRP work; EPDM has more flexibility on timing.
4. Strip and prepare
We strip the failed covering, repair or replace the deck, and correct the falls to the outlet.
5. System installation
We install the GRP or EPDM system with correctly formed upstands, trims and outlets — where flat roofs actually fail.
6. Cleanup and sign-off
Site cleared, final check, and the written guarantee plus 20-year system warranty handed over.
Timescales
Typical Timescales
Job
Typical duration
Garage flat roof
1 day
Extension flat roof (up to 25m²)
1–2 days
Larger EPDM area
2–3 days
Deck replacement (add-on)
+1 day
Dormer flat top
Half a day
GRP needs dry conditions above 5°C to cure correctly, so we plan fibreglass work around the forecast; EPDM is more weather-tolerant on exposed coastal sites.
Access
Access, Scaffolding & Permits in Donnington
Most flat roofs are single-storey extensions or garages reached from a tower or short scaffold; scaffold is quoted where the roof is at height or edge protection is needed. Scaffold is specified for: first-floor and higher flat roofs, or any flat roof where edge protection is required for safe working - always itemised in your written quote, never a hidden extra, and we arrange it.
Donnington's post-war and harbour-adjacent stock gives generally open access, with faster fascia decay near the water. Pavement scaffold and skip permits go through Chichester District Council; allow a few working days on streets like Selsey Road, Birdham Road where space is tight.
Pricing
Flat Roofing Prices in Donnington
Job
Typical range
Notes
Garage flat roof (GRP)
£900–£1,800
Seamless fibreglass
Extension flat roof (GRP)
£1,800–£4,000
Up to 25m²
Larger area (EPDM)
£3,500–£5,500
Single-ply rubber
GRP (per m²)
£80–£120
Supplied & fitted
Deck replacement
£25–£45/m²
If existing deck failed
What moves the price
Roof area and the chosen system (GRP vs EPDM)
Deck condition once the old covering is stripped
Number of upstands, outlets and edge details
Access height and edge protection
Whether falls need correcting to clear ponding
Worked example: A failed felt garage roof in Portfield stripped and refitted in GRP with new decking: around £1,450 including waste.
No deposit on flat roofs under £5,000. Payment on completion and inspection. No payment before materials are on site.
Covering PO19, PO20 and surrounding postcodes.
Guarantee
What the 10-Year Guarantee Actually Covers
The installation carries our written 10-year workmanship guarantee, with a 20-year manufacturer warranty on the GRP or EPDM membrane on top.
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.
Good to know
Disruption, Mess & Weather
A flat roof job is low-disruption — usually one to two days, single storey, minimal noise, and no need to be home for external work. You do not need to stay home for external work - we just need power and access agreed in advance.
EPDM installs in most conditions; GRP waits for a dry window. If rain interrupts, the deck is sheeted and protected until we can resume. Donnington's low-lying harbour-edge position brings extra humidity.
FAQ
Flat Roofing Donnington: Common Questions
Costs vary by scope and access. Garage Flat Roof (GRP): £900–£1,800. Extension Flat Roof (GRP): £1,800–£4,000. We provide a free survey and written itemised quote for all work in Donnington — no obligation to proceed.
Yes. Donnington is part of our regular working territory. We carry out flat roofing across all Donnington postcodes and the surrounding area. Our own team on every job — no subcontractors.
No. The survey visit and quote are free with no obligation. For emergency work, we charge only for the make-safe and repair — no separate call-out fee on top.
Minor repair or maintenance visits typically take 2 to 4 hours. Larger jobs — re-roofing, full flat roof replacement — take 3 to 7 days depending on size and complexity. We confirm the programme in the written quote.
Scaffold requirements depend on the job and property height. We confirm access requirements in the written quote. Scaffold cost is always included as a line item so there are no surprises.
Yes. Post-war residential with harbour-adjacent salt air acceleration. For flat roofing this means nail fixings corrode earlier than inland, lead oxidation accelerated. We specify materials and methods appropriate to Donnington's specific conditions at the survey.
Yes. Our NFRC membership is current and verifiable at nfrc.co.uk. We hold £5m public liability insurance and provide a written 10-year workmanship guarantee on all flat roofing in Donnington. All credentials available on request.
Survey and Specification for Donnington Chichester Flat Roofs
Every flat roof survey covers: the existing deck condition (whether the existing decking boards are sound or require replacement), the current falls (whether adequate drainage exists or whether tapered insulation is needed to correct the falls), the upstand heights (whether the covering can be taken up to the required minimum height at edges and abutments), and the outlet position and sizing. In Donnington Chichester, where harbour-adjacent post-war residential with salt air acceleration, we also assess whether coastal UV intensity or harbour moisture exposure affects the system recommendation. A flat roof that drains correctly and has proper upstand details lasts decades longer than one where these fundamentals were not addressed at installation.
GRP Installation Process
GRP fibreglass is applied as a liquid laminate that cures to a rigid seamless surface. We apply two layers of chopped strand mat saturated with resin, followed by the coloured gelcoat finish. The entire surface is seamless — no joints to open, no laps to fail. Upstands are formed to the correct height and radius at all edges. Outlets are GRP-lined. The gelcoat provides UV protection that significantly outlasts felt surface treatment in Chichester's coastal UV environment. Installation requires temperatures above 5°C — we plan flat roof work around weather forecasts to ensure the correct curing conditions.
Flat Roof Costs in Donnington Chichester
A standard single-car garage flat roof in GRP typically costs £900 to £1,800 in Donnington Chichester. Rear extension flat roofs up to 25m² cost £1,800 to £4,000. Larger areas of 25 to 60m² run £3,500 to £7,500. These prices include deck inspection, any necessary deck replacement, falls correction where needed, full GRP lamination and gelcoat finish. EPDM rubber costs approximately 10 to 15 per cent less than GRP on the same area with comparable performance over the long term.
Get In Touch
Free Quote — No Call-Out Fee
Honest pricing from a local Chichester roofer. Free survey, written quote, no obligation in Donnington.
