Flat Roof Replacement Cost Calculator UK
Get a 2026 flat roof replacement cost estimate in 30 seconds. Felt, EPDM rubber, single-ply or GRP fibreglass — by roof area, deck condition, insulation and region. Supply-and-fit rates. No email required.
Estimate Your Flat Roof Cost in 30 Seconds
6 steps. Covers strip-off and disposal, the new covering, deck repairs, insulation upgrade, trims and edging, labour and VAT.
How This Calculator Works
Our flat roof calculator combines the covering, roof area, deck condition, insulation and region with real 2026 UK supply-and-fit pricing from vetted roofers across our 519-town database.
Covering Rates (per m², fitted)
- Felt (3-layer torch-on) — £55–£95/m²
- EPDM rubber — £80–£120/m²
- Single-ply PVC/TPO — £90–£135/m²
- GRP fibreglass — £95–£140/m²
- Warm-roof insulation upgrade — +£55/m²
Rates include strip-off, disposal, the new covering, trims, edging, labour and VAT.
Assumptions & Adjustments
- Deck repairs: new boards +£850 typical, new deck with joist repairs +£1,800
- Replacing more than half the roof triggers a Part L insulation upgrade (target U-value 0.18 W/m²K)
- Access: tower scaffold +£450, full scaffold +£900
- Region multipliers: London +27% … Northern Ireland −12% (Midlands baseline)
- Estimate only — a firm quote always follows a roof inspection
A sagging or spongy deck usually means hidden rot — budget for deck replacement before choosing the covering.
Typical Flat Roof Replacement Costs (2026)
Supply & fit incl. strip-off, disposal, new covering, trims, labour & VAT, Midlands baseline. Deck repairs and scaffold access priced separately.
| Covering / scenario | Typical size | Cost range |
|---|---|---|
| Felt, 3-layer (garage) | 18 m² | £990–£1,710 |
| EPDM rubber (garage) | 18 m² | £1,440–£2,160 |
| GRP fibreglass (garage) | 18 m² | £1,710–£2,520 |
| EPDM + warm-roof upgrade (extension) | 35 m² | £4,730–£6,130 |
| Single-ply PVC/TPO (large extension) | 40 m² | £3,600–£5,400 |
Want the full method and per-material detail? Read the complete 2026 roofing cost guide.
Frequently Asked Questions
How much does it cost to replace a flat roof in 2026?
Which is better — felt, EPDM rubber or GRP fibreglass?
Do building regulations apply to a flat roof replacement?
How do I know if the deck needs replacing too?
How long does a flat roof replacement take?
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