Typical garage conversion costs
The figures below are what our clients across Greater Manchester, Lancashire and Cheshire actually pay, including all building work, Building Control fees, electrics, plastering and decoration. Every project is quoted individually after a free survey, so treat these as a realistic guide rather than a menu.
| Type of conversion | Typical cost | Time on site |
|---|---|---|
| Single garage → bedroom, office, playroom or living room | £8,000 – £14,000 | 2–3 weeks |
| Single garage → gym (insulated, rubber floor) | £7,000 – £11,000 | 2 weeks |
| Part of garage → utility room | £6,000 – £10,000 | 1–2 weeks |
| Single garage → bedroom with en-suite | £12,500 – £19,000 | 3–4 weeks |
| Double garage → two rooms or master suite | £16,000 – £26,000 | 3–5 weeks |
| Double garage → self-contained annexe | £28,000 – £45,000 | 4–6 weeks |
| Detached garage → office, studio or gym | £10,000 – £16,000 | 2–4 weeks |
| Knock-through to open-plan kitchen (excluding kitchen units) | £11,000 – £18,000 | 3–4 weeks |
What affects the cost of a garage conversion?
- Size and type of garage. A double or detached garage has more wall, roof and floor to insulate, and detached buildings need a new electrical supply.
- Condition of the existing structure. A sound brick garage with a good slab is cheap to convert. A cracked slab, a leaking roof, a rotten wall plate or a prefab concrete garage all add cost — sometimes enough that a rebuild is the better option.
- Plumbing and drainage. Bathrooms, kitchenettes and utility rooms need water and waste. If a drain is close by this is modest; if not, a longer run or a macerator adds to the price.
- Structural work. Wider openings, knock-throughs and new lintels need an engineer's design and steel.
- Windows and doors. A single window in the infill wall is standard; French doors or bi-folds cost more.
- Heating choice. A radiator on the existing system is the cheapest option; underfloor heating adds £800–£1,500 for a single garage.
- Finishes and joinery. Flooring, built-in wardrobes, storage and kitchen units are quoted separately so you control the spend.
- Planning. Most conversions don't need it; where an application is required, add the council fee and drawings.
What our fixed-price quote includes
We quote the whole job, itemised, and the price doesn't change unless you change the specification. A typical single garage quote covers: removal of the garage door and construction of the insulated infill wall with a new window; new damp-proof membrane and insulated floor; insulated and dry-lined walls and ceiling; a new internal doorway if needed; electrics with certification; a radiator on your existing system; plastering; skirting and architrave; decoration; Building Regulations notice and inspection fees; and removal of all waste. Flooring, bathrooms, kitchens and joinery are listed as options so you can see exactly what each adds.
Is a garage conversion worth it?
For most homes, yes. A garage conversion is typically the cheapest way to add a room — around half the cost per square metre of a single-storey extension and far less disruptive than a loft conversion. Estate agents across the region consistently report that a properly certified conversion (especially a bedroom or open-plan kitchen) adds more to the sale price than it costs, and it makes the house work better in the meantime.
Ways to pay: we invoice in stages tied to progress (typically deposit, first fix, completion). We're happy to work alongside a home-improvement loan or a further advance on your mortgage — ask us for a formal quotation letter for your lender.