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 | £7,767 | £1,547 | £11,253–£12,253 |
| 3.6m × 3m | 8.1 m² | £9,483 | £1,171 | £13,517–£14,517 |
| 4m × 3m | 9.1 m² | £10,119 | £1,110 | £14,358–£15,358 |
| 5m × 3m | 11.7 m² | £11,417 | £977 | £16,070–£17,070 |
| 5m × 4m | 16.2 m² | £12,977 | £799 | £18,130–£19,130 |
| 6m × 3m | 14.2 m² | £12,762 | £896 | £17,845–£18,845 |
| 6m × 4m | 19.8 m² | £14,715 | £743 | £20,424–£21,424 |
| 7m × 4m | 23.4 m² | £16,241 | £695 | £22,438–£23,438 |
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.