House Extensions
How much does a house extension cost in Plymouth?
A 2026 cost guide for single-storey, double-storey and wrap-around extensions across Plymouth and the South West.
What you'll pay in Plymouth in 2026
For most Plymouth homes, a single-storey rear extension lands between £2,200 and £3,000 per m² fully finished. A double-storey extension is typically £2,000–£2,800 per m² because the roof and foundations are shared across two floors. Wrap-around extensions sit at the top of the range due to the structural openings and glazing involved.
What drives the price
- Ground conditions (Plymouth's mix of clay, shillet and made-ground often requires deeper or engineered foundations)
- Glazing — sliders and lanterns add £4,000–£12,000
- Kitchen / bathroom fit-out
- Steelwork for open-plan layouts
- Planning conditions in conservation areas (e.g. Stoke, Mannamead)
Realistic budgets
| Type | Size | Budget |
|---|---|---|
| Single storey rear | 20 m² | £45k–£60k |
| Single storey rear | 30 m² | £65k–£90k |
| Double storey side | 40 m² | £85k–£115k |
| Wrap-around | 35 m² | £95k–£130k |
How to keep your build on budget
Fix the spec before you start. Most overruns come from late changes — bigger sliders, upgraded kitchens, or moving a soil stack. Get a fixed quote, not an estimate, and ask for a stage payment schedule.
Get a fixed quote
We build extensions across Plymouth, Plymstock, Plympton, Saltash and the South Hams. Request a free quote and we'll give you a fully itemised price.