How we estimate roof replacement cost
Every estimate combines a national price for each part of the job with a local labor adjustment for your region. Here is exactly how that works and where the numbers come from.
The formula
For each line item we multiply a quantity (driven by your roof size, pitch, stories, and material grade) by a national unit cost, then apply a quality-grade factor. A regional labor multiplier is applied to the labor portion only — materials are priced nationally. We show the itemized result as a ±15% range.
National unit costs
| Line item | National unit cost | Source |
|---|---|---|
| Tear-off | £15.00 / m² | ref |
| Underlayment | £8.00 / m² | ref |
| Roofing material | £35.00 / m² | ref |
| Installation labor | £40.00 / m² | ref |
| Flashing & vents | £7.00 / m² | ref |
| Disposal | £5.00 / m² | ref |
Regional labor multipliers
Each region's labor multiplier is its mean construction-trades wage relative to the GB mean, from ONS ASHE Table 15 (SOC 531, Construction and Building Trades; 2024 revised edition) — a broader occupation than the roofer-specific series the US version uses, because ONS suppresses narrow-occupation regional wage data. Multipliers are bounded to a sane range and applied to the labor share of each line item, so materials stay nationally priced while labor tracks local wages.
Data vintage & limitations
Compiled June 2026 from public cost aggregators and government wage data — these are derived estimates, not live contractor quotes. Local prices vary with project complexity, access, and material availability; always confirm with a licensed contractor before budgeting.
Tax & data notes
- VAT
- Roofing work on an existing home is standard-rated at 20% VAT across the whole UK — the same in every region. Published trade cost-guide figures are usually quoted before VAT, so we add it as a separate line and the headline estimate is VAT-inclusive — the price you actually pay. (US estimates carry no VAT; sales tax there varies by state and is excluded.)
- How firm these costs are
- The national £/m² unit costs are assembled from UK cost aggregators (Checkatrade, HomeOwners Alliance, priceyourjob) by surface, not taken from a single independent whole-roof figure, and the calculator is calibrated so the default estimate matches a cited national average. Individual line prices are therefore provisional; treat the figures as a guide and confirm with a licensed contractor before budgeting.