Is Flat Roofing the Right Fix?
A flat roof problem usually shows as a damp patch on the ceiling below, ponding water that never drains, or a felt surface that has blistered, split or lifted at the edges.
- Damp patch on the ceiling directly under a flat roof
- Water pooling and not draining within 48 hours
- Felt blistered, cracked or lifting at the upstands
- Soft or springy feel underfoot indicating deck rot
- Repeated patch repairs to an ageing felt roof
When it is not the answer: If the deck is sound and only a seam has failed, a targeted repair may hold rather than a full re-cover Read the full guide.
Local Factors in Cosham
Portsdown Hill shelter reduces salt slightly, but 1930s concrete tiles here are shedding surface aggregate at 85–90 years old. Cosham's 1930s semis have generous simple roofs with good access, though mature avenue trees complicate scaffold and skip placement. It is why we specify marine-grade fixings and correct lead codes as standard on Cosham roofs — the coastal environment punishes anything less.
What to Expect: Flat Roofing in Cosham
1. Survey
We assess the covering and, critically, the deck condition underneath — the biggest cost variable on a Portsmouth flat roof.
2. Written quote
An itemised quote specifying the system — GRP, EPDM or felt — and any deck replacement, priced upfront.
3. Scheduling
We book the work and arrange access; most flat roofs are a one to three day job.
4. The work
Strip, assess and replace any rotten deck, then lay the chosen coastal-grade membrane with proper upstands and drainage falls.
5. Cleanup & sign-off
Site cleared, waste removed, and your 10-year workmanship guarantee issued alongside the membrane manufacturer warranty.
Typical Timescales
| Job | Typical duration |
|---|---|
| Small flat roof / porch | 1 day |
| Garage-sized GRP or EPDM | 1–2 days |
| Large or multi-level flat roof | 2–4 days |
| Deck replacement (add-on) | +1 day |
| Dormer flat roof | 1–2 days |
GRP needs dry, workable temperatures to cure — we schedule around the forecast and never lay over a damp deck.
Getting Safely onto Cosham Roofs
Most flat roofs work from towers or a small scaffold; access is straightforward on single-storey extensions and garages. Scaffold is specified for: first-floor and above flat roofs, or where edge protection is needed for safe working - always itemised in your written quote, never a hidden extra, and we arrange it.
Cosham's 1930s semis have generous simple roofs with good access, though mature avenue trees complicate scaffold and skip placement. Pavement scaffold and skip permits go through Portsmouth City Council; allow a few working days on streets like High Street, Wootton Street, Spur Road where space is tight.
Cosham Flat Roofing: Cost Guide
| Job | Typical range | Notes |
|---|---|---|
| Felt flat roof (garage) | £1,200–£2,200 | 10–15yr coastal life |
| EPDM rubber (garage) | £1,800–£3,000 | 20–25yr life |
| GRP fibreglass (garage) | £2,400–£3,400 | 22–28yr life |
| GRP per m² | £95–£135 | Incl. gelcoat + upstands |
| Deck replacement | £40–£70/m² | Where rot found |
What moves the price
- Roof height and access on Cosham stock
- Coastal-grade materials (marine fixings, code 5–6 lead)
- Extent of hidden salt-corrosion damage found on survey
- Scaffold vs tower vs ladder access
- Conservation constraints where applicable
Worked example: A typical job on a property off High Street in Cosham, including access and waste removal, sits in the middle of the ranges above once surveyed.
No deposit on repairs under £500. Staged payments on re-roofs — nothing up front before materials are on site. All prices include VAT; written itemised quote before any work.
Covering PO6 and surrounding postcodes.
Your Guarantee, Explained
The flat roof carries a 10-year workmanship guarantee; GRP and EPDM membranes carry manufacturer warranties of 20–25 years 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.
Living Around the Work
One to three days of work over a single roof area, minimal internal disruption — we protect the space below and clear all waste. 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, which we plan around Portsmouth's coastal forecast. Portsdown Hill shelter reduces salt slightly, but 1930s concrete tiles here are shedding surface aggregate at 85–90 years old.