How Much Does a Wrap-Around Extension Cost in the UK?
A wrap-around extension combines a rear extension and a side extension into a single L-shaped structure that "wraps" around the corner of a house. It is the largest possible single-storey ground-floor extension and can add 30–50m² of floor space. Because it combines two extensions, the cost per square metre tends to be slightly lower than building each separately, but the total project cost is substantial.
Typical Cost (UK, 2026)
Approximately £1,800–£2,800 per m² including labour and materials
All costs are indicative estimates. Obtain at least 3 quotes from qualified builders. Prices exclude VAT (20%).
Factors Affecting the Cost
Total footprint
Wrap-around extensions range from around 25m² to over 50m². Every additional square metre adds to the cost.
Complexity of form
An L-shaped roof with internal valley gutter or a flat roof with multiple roof lights is more complex and costly than a simple single pitch.
Existing structure condition
If the existing house requires underpinning, drainage diversions, or asbestos removal, costs increase significantly.
Glazing specification
Bifold doors on both the rear and side elevations — popular with wrap-around extensions — can add £10,000–£25,000 to the glazing budget.
Kitchen or open-plan fit-out
A wrap-around extension is often used to create a large kitchen-diner. The kitchen itself can add £10,000–£30,000 on top of the build cost.
Cost Breakdown
| Item | Basic | Mid-range | High-end |
|---|---|---|---|
| Demolition of existing outbuilding (if required) | £0 | £2,500 | £6,000 |
| Foundations and groundworks | £8,000 | £14,000 | £22,000 |
| Structure (walls, steelwork) | £12,000 | £20,000 | £32,000 |
| Roof | £8,000 | £14,000 | £22,000 |
| Glazing and external doors | £8,000 | £16,000 | £30,000 |
| Internal finishes and services | £12,000 | £20,000 | £35,000 |
| Architect, engineer, and planning fees | £4,000 | £7,000 | £12,000 |
Costs are indicative and exclude VAT. Regional variations apply.
Typical Timeline
16–24 weeks on site
Frequently Asked Questions
Get a Personalised Cost Estimate
Use our interactive calculator to estimate your extension cost by size, type, and location.
Calculate Your Extension Cost →