No inflated quotes that get haggled down. No surprises on site. Hutch prices at fair market rates, confirms your price in writing, and doesn't move from it.
Every project is broken into four milestones tied to real on-site progress. You pay when we deliver — never before. Your final 10% is held until full snagging sign-off.
Your PM confirms each milestone before any invoice is raised.
Indicative ranges based on recent London projects. Use the estimator above for a project-specific figure.
| Type | Description | Typical range |
|---|---|---|
| Velux | Roof lights into existing slope, no structural change to roofline | £35k–£50k |
| Rear dormer | Flat-roof box to rear slope — most common type | £45k–£65k |
| Hip-to-gable | Extends roofline on semis and end-terraces | £55k–£75k |
| L-shaped dormer | Rear and side combined — maximum space for terraces | £65k–£85k |
| Mansard | Near-vertical rear wall — maximum volume, planning required | £75k–£100k |
| En-suite adds £4k–£8k · Party wall adds £1.5k–£2.5k per neighbour | ||
| Type | Description | Per m² |
|---|---|---|
| Rear single storey | Into garden at ground level — most common extension | £2,000–£3,300/m² |
| Side return | Fills the narrow passage beside Victorian terraces | +5% on base rate |
| Wraparound | Rear and side combined — maximum ground-floor footprint | +8–10% on base rate |
| Double storey | Two floors to rear — planning required | Blended rate −10–15% |
| Structural opening adds £2k–£15k · Bifolds add £3k–£7k · Rooflights add £1k–£7k | ||
| Size | Description | Typical range |
|---|---|---|
| Small | Compact galley or single-run layout | £8k–£12k |
| Medium | Standard kitchen/diner, L or U-shape | £12k–£20k |
| Large | Open-plan or island layout | £18k–£35k |
| Layout change adds £2k–£6k · Structural work adds £4k–£12k · Quartz worktop adds £2k–£5k | ||
| Size | Description | Typical range |
|---|---|---|
| Small | WC / cloakroom or compact en-suite | £4k–£6k |
| Medium | Standard bathroom or en-suite with shower | £6k–£10k |
| Large | Family bathroom or larger en-suite | £9k–£16k |
| Layout change adds £1k–£3k · Full relocation adds £3k–£6k · Full tiling adds £1k–£4k | ||
If you have a genuine like-for-like quote from another reputable builder — same scope, same spec, same quality of trades — we'll match it.
The key word is like-for-like. Many cheaper quotes exclude structural drawings, carry thinner insurance, or use unqualified labour. We'll sit down and compare line by line.