THE UK GARDEN ROOM GUIDE
Garden room cost calculator
Start with your size and build route. Get an itemised working budget, with clear assumptions and room for the unexpected.
YOUR PROJECT
How will you build?
Finish allowance
For a simple insulated office or hobby room. Sauna equipment, gym equipment, simulator hardware, plumbing and unusual ground conditions are excluded.
See the calculation assumptions
Room allowance: DIY £650/m²; kit £850/m²; installed £1,450/m². Premium adds 30% to the room allowance. Foundations: £500 + £140/m². Services: £1,800 when selected. Contingency: 15%. Range: 85%–120% of total, rounded to £100. All figures are assumed VAT-inclusive budget allowances, not surveyed averages or quotes. Model: September 2026.
YOUR INDICATIVE BUDGET
£11,500–£16,300
12.0 m² external footprint · DIY build
Room & finish allowance£7,800
Foundation allowance£2,180
Power & heating allowance£1,800
15% contingency£1,767
Working budget£13,547
An early budgeting tool. Replace these allowances with itemised local quotes before committing.