Extensions & Conversions · Updated 2026
Garden room cost
Typical range£5,000–£80,000· Average fully insulated garden room
Garden room, garden office and summerhouse prices 2025. In the UK, expect to pay between £5,000 and £80,000, with the typical project around £18,000 (average fully insulated garden room). Regional variation, specification tier and site access conditions all shift the final quote.
Quick answer: Garden room cost in the UK typically costs between £5,000 and £80,000 (Average fully insulated garden room). London and the South East run 20–35% above this range; the North, Wales and most of Scotland sit 5–15% below.
Homeowners researching this typically also price up garage conversion cost. For wider context, browse our bathroom pricing, kitchen pricing and boiler & heating costs.
Cost table
Indicative price ranges (UK, GBP)
| Item | Typical range (GBP) |
|---|---|
Budget garden room (timber kit) — Pre-fabricated, basic insulation, no heating | £5,000–£12,000 |
Mid-range garden room — Well insulated, power, heating, year-round use | £12,000–£25,000 |
High-spec garden office — Architect designed, bifolds, premium finish | £25,000–£50,000 |
Garden annexe — With kitchen, bathroom, separate living space | £40,000–£80,000 |
Labour costs
Labour typically accounts for 35% of the total project cost in the UK.
Labour line items
| Item | Typical range (GBP) |
|---|---|
Base / foundations | £1,500–£5,000 |
Structure erection | £3,000–£12,000 |
Electrician (supply + fit-out) | £800–£2,500 |
Decorator | £400–£1,500 |
Materials costs
Materials and fittings make up the remainder of the budget, with specification tier driving most of the variation.
Materials & fittings
| Item | Typical range (GBP) |
|---|---|
Timber frame structure | £4,000–£20,000 |
Insulation (walls/floor/roof) | £800–£3,000 |
Cladding (timber, composite) | £1,000–£6,000 |
Windows and doors | £1,000–£8,000 |
Roofing (rubber/felt/slate) | £600–£4,000 |
Factors affecting cost in the UK
- ·Region — London and the South East run 15–30% above national averages.
- ·Specification tier — premium materials and finishes can double the base cost.
- ·Access and site conditions — flats, restricted parking and listed buildings add time.
- ·Scope changes mid-project — late design decisions are the biggest cost overrun driver.
- ·Trade availability — quotes rise 10–20% in peak spring and summer months.
Ways to reduce cost
- ·Choose a SIPS or modular kit from a single supplier rather than a bespoke build.
- ·Stay under 2.5 m ridge height and 30 m² to fall under permitted development.
- ·Site the room within 2 m of the house to shorten service runs.
- ·Use timber cladding rather than aluminium or zinc for a 30% saving.
- ·Power only — skip plumbing unless you need a WC or kitchenette.
Frequently asked questions
- Do I need planning permission for a garden room?
- Garden rooms are usually permitted development if: they are single storey under 2.5m height (or 4m for dual pitch), cover less than 50% of the garden, are not forward of the principal elevation, and are not used as a bedroom. Check with your local authority if in doubt.
- Can a garden room be used as a home office?
- Yes — this is the most popular use. A well-insulated garden room can be used year-round. HMRC allows garden offices to qualify for capital allowances if used exclusively for business, and there may be a Business Rates implication on larger structures.
- How long does a garden room last?
- A quality garden room with pressure-treated timber frame, good insulation, and quality roofing should last 25–40 years with standard maintenance. Timber cladding typically needs treating every 3–5 years.
- What is the difference between a garden room and a summerhouse?
- A summerhouse is typically uninsulated, not heated, and used seasonally. A garden room is a year-round structure with proper insulation, heating, and often broadband connectivity. The price difference reflects this: summerhouses cost £2,000–£8,000; garden rooms £12,000–£50,000+.