Garden room cost, size by size
Materials-only costs for a fully insulated timber-frame garden office, each computed line-by-line by our parametric engine at indicative UK merchant rates. Click a size for the full stage-by-stage breakdown.
| Size | Internal area | Materials (ex VAT) | Per m² | All-in DIY budget |
|---|---|---|---|---|
| 3m × 2.4m | 5.0 m² | £7,855 | £1,564 | £11,369–£12,369 |
| 3.6m × 3m | 8.1 m² | £9,588 | £1,184 | £13,656–£14,656 |
| 4m × 3m | 9.1 m² | £10,230 | £1,122 | £14,504–£15,504 |
| 5m × 3m | 11.7 m² | £11,541 | £988 | £16,234–£17,234 |
| 5m × 4m | 16.2 m² | £13,116 | £808 | £18,313–£19,313 |
| 6m × 3m | 14.2 m² | £12,900 | £906 | £18,028–£19,028 |
| 6m × 4m | 19.8 m² | £14,868 | £751 | £20,625–£21,625 |
| 7m × 4m | 23.4 m² | £16,408 | £702 | £22,658–£23,658 |
Twenty Paces is a planning aid, not professional structural or planning advice. Costs are materials-only at indicative merchant rates (excluding labour and delivery); span tables, U-values and regulations thresholds are indicative. Verify your design with a structural engineer, your local planning authority and Building Control before you build.