5×3m Garden Room
Versatile Space for Work or Play
Overview
The 5×3m offers an extra metre of width over the 4×3m, making it ideal for dual-purpose rooms — a home office with a meeting area, or a hobby room with proper storage.
What it's great for
Furniture & layout
Fits a full standing desk setup, two chairs for meetings, a small sofa, and dedicated storage. Or configure as a gym with a mat area, bike, and weights.
Planning permission
Still within Permitted Development for most properties. At 15m², you're just at the threshold where building regulations may apply if you're adding sleeping accommodation.
Build timeline
4–5 weekends for structure and fit-out.
Key materials
- ✓~75 linear metres of 4×2 CLS timber
- ✓15m² of EPDM roofing membrane
- ✓16 sheets of 18mm OSB
- ✓15m² of PIR insulation (100mm walls, 150mm roof)
- ✓30 linear metres of cladding
For exact quantities and a full materials list, see the Build Pack.
Estimated DIY cost
Standard spec, with electrics — materials only
Your DIY Cost Estimate
Materials only — does not include your time
Professional cost is an estimate based on typical UK contractor rates (approx. 2.75× materials). Actual quotes will vary.
Try the full calculator to adjust spec and extras.
Free build checklist
Get our material checklist and build timeline free.
Other size guides
Ready to build your garden room?
Get the complete DIY build pack — full plans, materials list, and step-by-step guides for £49.