How Much Does a Garage Conversion Cost in 2026 UK?
In 2026 UK, a garage loft conversion typically costs £18,000–£55,000 depending on garage type and finish: single attached garage £18k–£35k, integral garage £22k–£42k, double garage £30k–£55k. Most projects fall under permitted development and add 10–15% to property value.
Garage conversion cost at a glance — UK 2026
- Single attached garage to habitable room: £18,000–£35,000
- Integral garage (under house): £22,000–£42,000
- Double garage to large room or annexe: £30,000–£55,000
- Detached garage to home office / studio: £24,000–£40,000
- Garage + loft combined conversion: £55,000–£95,000
- Build regs sign-off, plans & SAP: £1,200–£2,800 on top
London & SE premium: add 20–30% across every range. Listed buildings, conservation-area frontages and structural alterations push costs higher.
2026 cost by garage type, location and finish
What's actually driving the 2026 garage conversion price
Three line items now eat 65–70% of total spend: insulation upgrade to Part L 2025, floor build-up to lift the slab above DPC, and electrics + heating tie-ins. Material costs have stabilised after the 2024 peak, but compliant insulation is non-negotiable.
- Insulation (£2,200–£4,800): Part L 2025 demands 0.18 W/m2K U-value on walls and 0.15 on roof. PIR boards plus reflective foil are the go-to spec.
- Floor build-up (£1,800–£3,200): garage slabs sit below the house DPC. A 100mm screed + DPM + insulation lift is essential to avoid cold-bridging and damp.
- Heating & electrics (£2,800–£5,400): tying into the existing boiler / consumer unit, plus underfloor heating where slab depth allows.
- Windows & doors (£1,800–£4,500): replacement of the old garage door with brick infill or French / bi-fold doors.
2026 reality: a properly-converted garage adds 10–15% to property value (Nationwide HPI / Savills 2026), so a £30k single-garage conversion on a £450k home typically returns £45k–£68k of value — one of the best £-per-m2 ROIs in UK home improvement.
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Frequently asked questions
Single attached garage £18,000–£35,000, integral garage £22,000–£42,000, double garage £30,000–£55,000 fully finished including insulation, heating, electrics and decorating. London and SE add 20–30%.
Most garage-to-habitable conversions fall under permitted development if you keep the external footprint and roofline. You will still need building regs sign-off for insulation, fire safety, ventilation and electrics. Listed buildings and conservation areas always need consent.
Yes — Nationwide and Savills 2026 data shows a quality garage conversion adds 10–15% to UK property value, more in urban locations where off-street parking is less valued. Cost-vs-value ROI is typically 120–160%.
4–8 weeks on-site for a single garage to habitable room. Integral garages 6–10 weeks because they tie into the existing heating and electrics. Double garages with kitchenette or en-suite 10–14 weeks.
Yes — integral garages are the easiest conversion because services are already adjacent. Expect £22k–£42k for a fully-insulated bedroom with en-suite. Floor build-up and damp tanking are the two technical must-haves.
Yes — typically 35–50% cheaper per m2 than a comparable single-storey extension because the shell, roof and foundations already exist. The trade-off is you lose covered parking and storage.
Sources used in our 2026 cost figures
- FMB — Federation of Master Builders cost guide
- Nationwide House Price Index 2026
- Planning Portal — permitted development
- UK Building Regs — Part L 2025
Methodology: Cost ranges drawn from FMB published guidance, BestBuilders' contractor network field reports (May 2026, 180+ active garage conversion firms) and Nationwide / Savills 2026 value-uplift data. Last fact-checked: .