Why Garden Rooms Are in Demand
Since 2020, London homeowners have prioritised dedicated working-from-home space. Garden rooms offer several advantages over converting existing rooms:
- Separate from the main house — better for focus and professional video calls
- No loss of bedroom or living space
- Can be completed within 2–4 weeks with a specialist installer
- Often permitted development (no planning permission required)
Permitted Development Rules for Outbuildings
Most garden rooms in London qualify as permitted development, meaning no planning application is required. Key conditions:
- Must not be forward of the principal elevation (front of the house)
- Maximum eaves height of 2.5 metres if within 2 metres of a boundary
- Maximum height of 4 metres (dual-pitch roof) or 3 metres (flat or mono-pitch roof)
- Must not cover more than 50 per cent of the garden area
- Cannot be used as a separate self-contained dwelling
Important: In Conservation Areas, additional restrictions may apply. Check with your local planning authority.
Design Considerations
Size and Footprint
Most garden offices are 10–25 square metres. The ideal size depends on:
- How many people will work in it
- Whether it will include a small kitchenette or WC
- The available garden space and access for delivery
Insulation and Year-Round Use
For a garden room to be usable year-round, insulation is critical:
- Floor: Insulated timber frame or concrete base
- Walls: 100–150mm insulation to achieve good thermal performance
- Roof: Adequate insulation for the flat or pitched roof specification
A well-insulated garden room achieves U-values comparable to a new-build extension. Poorly insulated structures are cold in winter and overheating in summer.
Power and Connectivity
- Electrical supply: A dedicated circuit from the main consumer unit via armoured cable (buried underground). This requires a Part P-compliant electrician.
- Lighting and sockets: Include enough twin sockets for monitors, charging, and desk lamps
- Broadband: A wired ethernet connection from the router in the house is more reliable than WiFi; a CAT6 cable can be run in the same cable run as the electrical supply
- Heating: Electric panel heaters or an infrared panel are most common; underfloor heating works well for permanently used spaces
Natural Light
- A garden room facing south or south-west benefits from good natural light
- Bi-fold or sliding doors to the garden make the space feel larger
- Roof lights can supplement natural light in deeper structures
Building Regulations
Most garden rooms do not require Building Regulations approval because they are:
- Less than 15 square metres (exempt from structural requirements)
- Or less than 30 square metres and at least 1 metre from any boundary
However, if the garden room includes a WC, a connection to the drainage system is required and Building Regulations will apply.
Always check with the local authority if in any doubt.
Typical Costs
Garden room costs vary significantly based on specification:
| Type | Cost Range |
|---|---|
| Basic timber kit (uninsulated) | £5,000–£10,000 |
| Insulated year-round use (10–15 sqm) | £12,000–£25,000 |
| Premium timber or cladded pod (20–30 sqm) | £25,000–£50,000+ |
| With WC and kitchenette | Add £3,000–£8,000 |
Electrical supply installation typically costs £800–£2,000 depending on distance and trench length.
RCB Design & Build
RCB supports garden room projects as part of wider property upgrades — including electrical supply connections, drainage for WC facilities, and landscaping integration. We also advise on permitted development compliance so clients know exactly where they stand before committing to a design.