Roof Cost Calculator UK
A new roof is one of the biggest single spends on a house, and the quotes can swing by thousands for the same job. This UK roof cost calculator gives you a realistic supply-and-fit estimate before the roofer arrives — for a full re-roof, a new-build roof or an overlay — across concrete tiles, clay, natural slate and flat-roof coverings. It factors in scaffolding, waste removal, your region and how complicated the roof is, then shows a low-to-high range, a typical figure and a cost per square metre. Enter your roof area, or work it out from your footprint and pitch, and you will know roughly what to budget and whether a quote is fair.
Enter your roof details to estimate the cost.
How this calculator works
The tool starts from your roof area — either entered directly, or worked out from your ground-floor footprint and roof pitch using the slope factor (1 ÷ cosine of the pitch), which is why a steeper roof has more area than the floor beneath it. It multiplies that area by a supply-and-fit rate for your chosen covering, which already includes the underlay, battens and labour on a re-roof. Job type, complexity and region then adjust the figure: a strip-and-recover costs more than a new-build roof, a roof full of valleys and dormers costs more than a plain gable, and London labour costs more than the North East. Scaffolding and skip hire are added as separate lines because they are real costs that "per square metre" quotes often hide. Takeaway: the covering is only part of the price — access, waste and complexity move the number as much as the tiles do.
What a roof actually costs in the UK (2026)
As a rough guide, re-roofing a typical three-bedroom semi with concrete interlocking tiles lands around £5,000 to £9,000 including scaffolding, while natural slate on the same roof can push past £12,000. Flat roofs are usually priced by the covering: EPDM rubber and GRP fibreglass sit around £80 to £150 per square metre supply-and-fit. The single biggest variable most people miss is the condition of what is underneath — if the battens, felt or timber need replacing, or a chimney needs re-flashing, the price rises regardless of the tile you pick. Takeaway: budget for the covering, but keep a contingency for the timber and flashings you cannot see from the ground.
Re-roof, new roof or overlay?
A full re-roof strips the old covering back to the rafters, replaces the underlay and battens, and re-covers — the standard job on an ageing roof and the one this tool defaults to. A new roof on a new build or extension skips the strip-off, so it is a little cheaper per square metre. An overlay, where new tiles or a new felt go over the existing covering, is the cheapest option but is only sensible on a sound, lightweight structure and is generally discouraged for slate or heavy tiles because of the added load. Takeaway: overlays save money up front but can store up problems — most reputable UK roofers will recommend a full strip and recover.
A point most roof cost calculators skip
Plenty of online roof-cost tools give you a single tidy number, which is worse than useless when you are comparing quotes. A real roof price is a range, and the honest information is in the breakdown: what is the scaffold costing, is the underlay being replaced, and is there a provisional sum for timber repairs? A quote that is dramatically cheaper than the rest usually is not — it has left the scaffold off, skipped the breathable membrane, or assumed the battens are fine without looking. Under BS 5534, the British Standard code of practice for slating and tiling, the fixings and underlay are not optional extras, they are the specification. Takeaway: compare the breakdowns, not the bottom lines — the cheapest quote is often the one missing the things that matter.
Worked example — re-roofing a Manchester semi
Take a three-bedroom semi in Manchester (North West) with a 75 m² roof, being fully re-roofed in concrete interlocking tiles, moderate complexity (one chimney, a couple of vents), with scaffolding included and VAT in the price.
- Covering, typical: 75 × £100 × 1.00 (re-roof) × 1.15 (moderate) = £8,625
- Scaffolding (semi, typical): £1,150
- Subtotal × region (North West 0.95): (8,625 + 1,150) × 0.95 = £9,286
- Waste removal (full re-roof): 75 × £4 = £300
- Ex-VAT total: 9,286 + 300 = £9,586
- With 20% VAT: ≈ £11,500, roughly £150/m²
So a realistic budget is around £10,000–£13,000 once the range is applied. Swap the concrete tiles for natural slate and the same roof moves closer to £16,000–£19,000. Takeaway: for a standard semi re-roof in concrete tile, budget in the £10k region including scaffold and VAT — and treat any quote far below that with caution.
Frequently asked questions
Related tools
- Roof Tile Calculator — how many tiles you need once you know the roof
- Roof Pitch Calculator — rise, run and pitch, and the slope area for this estimate
- Rafter Length Calculator UK — rafter sizing for a new or replacement roof
- Loft Conversion Cost Calculator UK — cost cluster sibling if the roof work is part of a conversion
- Extension Cost Calculator UK — cost cluster sibling for whole-project budgeting
Guides worth reading
- How Much Does a New Roof Cost in the UK? — the full price breakdown, a worked Manchester example and the lines cheap quotes leave out
Disclaimer: This calculator gives an indicative 2026 UK supply-and-fit estimate for planning only. It is not a quote. Actual roofing costs depend on roof condition, timber and flashing repairs, access, height, tile choice, waste and local labour rates. Building Regulations (including Approved Document A for structure and Part L where insulation is upgraded) and BS 5534 apply to roofing work. Always obtain at least three written quotes from qualified roofers, and check whether scaffolding, underlay and VAT are included in each.