How much does a UK house extension cost per m²?

Single-storey extensions in 2026 typically cost £2,000–£3,000 per m² outside London and £2,800–£4,000 per m² in London and the South East, depending on spec, glazing and finishes.

Do I need planning permission for an extension?

Many single-storey rear extensions fall under Permitted Development, but two-storey extensions, side returns, anything in a conservation area or affecting a listed building usually needs full planning permission.

How much value does an extension add?

A well-built extension typically adds 10–20% to a UK property's value, though in price-capped markets the uplift may not exceed the build cost — always check comparable sold prices in your postcode first.

How long does a loft conversion take?

A standard dormer loft conversion takes 6–10 weeks on site. Hip-to-gable and mansard conversions take longer (10–14 weeks) due to additional structural work.

Do I need an architect or can a builder design it?

Small Permitted Development extensions can be designed by an experienced builder or a draughtsperson (£800–£2,000). Larger or planning-sensitive projects benefit from an architect or architectural technologist (£3,000–£8,000+).

Extensions & Conversions

Loft conversions, single and double storey extensions, outdoor works and major home improvements pricing.

Planning a wider project? Cross-reference bathroom renovation pricing, kitchen renovation pricing, boiler and heating costs and tradesperson day rates on the UK cost reference hub.

Loft conversion cost in the UK

Typical: £30,000–£75,000 · typical UK loft conversion

UK loft conversion costs: £30,000–£75,000 typical. Velux, dormer, hip-to-gable and mansard breakdown with labour, materials and hidden costs.

House extension cost in the UK

Typical: £30,000–£120,000 · typical UK extension

UK house extension costs: £1,800–£3,200 per m² typical. Single, double storey, side-return and wrap-around pricing with labour vs materials breakdown.

Roof repair cost in the UK

Typical: £150–£3,000 · typical roof repair

UK roof repair costs: £150–£3,000 typical. Tile replacement, leak repair, flashing, ridge tile and full re-roof pricing with labour breakdown.

Loft conversion cost breakdown in the UK

Typical: £30,000–£75,000 · dormer conversion

Detailed UK loft conversion cost breakdown: structural work 30%, roofing 15%, stairs 10%, electrics 8%, plumbing 8%, finishes 20% and fees 9%. Line-item tables.

Extension cost per m² in the UK

Typical: £1,500–£4,500 · per m²

UK extension cost per m²: £1,500–£2,500 for single storey, £2,000–£3,500 for double storey. Build cost, professional fees, VAT and location factors.

Cost of building a garage in the UK

Typical: £12,000–£40,000 · garage

How much does it cost to build a garage in the UK? Single garage £12,000–£25,000; double garage £20,000–£40,000. Prefab, brick, timber frame and detached options.

Driveway installation cost in the UK

Typical: £3,000–£15,000 · typical driveway

How much does a new driveway cost in the UK? Tarmac £50–£80/m²; block paving £80–£120/m²; resin £70–£100/m². Excavation, base, materials and labour breakdown.

Fencing installation cost in the UK

Typical: £40–£110 · per metre

How much does fencing cost in the UK? Close-board £60–£100/m; panel £40–£70/m; hit-and-miss £70–£110/m. Posts, gravel boards, labour and gates included.

Garden landscaping cost in the UK

Typical: £3,000–£50,000 · typical garden

How much does garden landscaping cost in the UK? Basic £3,000–£8,000; mid-range £8,000–£20,000; premium £20,000–£50,000+. Design, hardscape, planting, lighting and drainage.

Cost of new windows in the UK

Typical: £400–£1,500 · per window

How much do new windows cost in the UK? uPVC £400–£800/window; aluminium £600–£1,200/window; timber £800–£1,500/window. Installation, glazing options and property size factors.

Double glazing installation cost in the UK

Typical: £400–£1,000 · per window

UK double glazing costs: £400–£800 per window for uPVC; £5,000–£10,000 for a full house. A-rated units, installation, guarantees and energy savings explained.

Roof replacement cost in the UK

Typical: £4,500–£20,000 · typical house

How much does a roof replacement cost in the UK? Concrete tiles £80–£120/m²; slate £120–£180/m²; flat roof £60–£100/m². Labour, scaffolding, felt and hidden costs.

Cost of damp proofing in the UK

Typical: £400–£10,000 · typical treatment

How much does damp proofing cost in the UK? DPC injection £60–£90/m; tanking £80–£130/m²; membrane systems £40–£70/m². Survey, treatment types and guarantees.

Home renovation cost estimator for the UK

Typical: £10,000–£200,000 · 3-bed house

Estimate UK home renovation costs: light refresh £10,000–£25,000; mid-range £40,000–£80,000; full renovation £100,000–£200,000+. Room-by-room breakdown with rules of thumb.

Frequently asked questions — Extensions & Conversions

How much does a UK house extension cost per m²?: Single-storey extensions in 2026 typically cost £2,000–£3,000 per m² outside London and £2,800–£4,000 per m² in London and the South East, depending on spec, glazing and finishes.
Do I need planning permission for an extension?: Many single-storey rear extensions fall under Permitted Development, but two-storey extensions, side returns, anything in a conservation area or affecting a listed building usually needs full planning permission.
How much value does an extension add?: A well-built extension typically adds 10–20% to a UK property's value, though in price-capped markets the uplift may not exceed the build cost — always check comparable sold prices in your postcode first.
How long does a loft conversion take?: A standard dormer loft conversion takes 6–10 weeks on site. Hip-to-gable and mansard conversions take longer (10–14 weeks) due to additional structural work.
Do I need an architect or can a builder design it?: Small Permitted Development extensions can be designed by an experienced builder or a draughtsperson (£800–£2,000). Larger or planning-sensitive projects benefit from an architect or architectural technologist (£3,000–£8,000+).