Line-by-line build-up
Materials = supply cost; labour = what the trade charges for that element; fees & prelims = design, Building Control, party wall, scaffold, skips and site costs. Ranges are typical 2026 UK figures outside London. Every line links to the guide that explains it; labour figures assume the day rates in the Cost Index.
| Element | Materials | Labour | Fees & prelims | Notes |
|---|---|---|---|---|
| Design, planning application, calcs & Building Controlindex ↗ | – | – | £5,300–£8,600 | Full planning usually required; architect at 8–15% of build |
| Party wallindex ↗ | – | – | £1,250–£2,850 | Two-storey work on a shared wall, often two surveyors |
| Scaffoldingindex ↗ | – | – | £2,200–£3,250 | |
| Excavation, deeper foundations & drainageindex ↗ | £2,750–£4,000 | £5,150–£7,500 | – | Foundations sized for two storeys |
| Floor slab & screedindex ↗ | £1,600–£2,150 | £2,200–£3,000 | – | |
| Cavity walls, two storeys | £5,850–£8,300 | £10,850–£15,400 | – | |
| Steels (ground-floor opening + first-floor support)index ↗ | £1,450–£2,300 | £2,350–£3,800 | – | |
| First-floor joists & deck | £1,100–£1,600 | £2,400–£3,400 | – | |
| Pitched roof (tiles to match) & rainwaterindex ↗ | £3,000–£4,200 | £4,900–£6,900 | – | |
| Windows (first floor) & bifolds/doors (ground)index ↗ | £3,900–£7,000 | £1,550–£2,700 | – | |
| Electrics, both floorsindex ↗ | £800–£1,150 | £2,900–£4,050 | – | |
| Plumbing, heating & new bathroomindex ↗ | £2,000–£3,100 | £4,200–£6,550 | – | Incl. mid-range bathroom suite & tiling |
| Insulation & plastering, both floorsindex ↗ | £2,300–£3,150 | £3,400–£4,750 | – | |
| Flooring, doors, decorationindex ↗ | £2,100–£3,300 | £3,200–£4,950 | – | |
| Skips & site costsindex ↗ | – | – | £1,300–£2,150 | |
| Sub-totals (34% / 53% / 13%) | £26,850–£40,250 | £43,100–£63,000 | £10,050–£16,850 | |
| Build-up total | £80,000–£120,100 | vs published guide range £80,000–£120,000 | ||
The published guide for this job quotes £80,000–£120,000, which is the figure the build-up above is reconciled against.
Common additions & variations
- New kitchen (mid-range), £12,000–£25,000
- London uplift, +20–25%
- Full two-storey guide (incl. side & wraparound), £55,000–£130,000
How to use this
Treat the build-up as a sanity check on quotes, not a price list: a builder's quote that lands inside the total range with a similar materials/labour split is priced normally; one far below it is usually missing scope. Get three itemised quotes, compare them line by line against this table, and ask about anything that's absent. Figures exclude VAT where the trade is VAT-registered (most are above ~£90k turnover), and exclude fees you pay directly such as planning application fees.
Other build-ups
- Loft conversion, £45,000–£65,000
- Ground floor extension, £36,000–£56,000
- Internal renovation, £62,000–£122,000