Realistic UK investment ranges for integral and detached garage conversions, updated for 2025–2026.
Garage conversions are one of the most cost-effective ways to add living space. This guide covers typical fully managed projects across Milton Keynes, Northampton, Bedford and surrounding areas, including damp proofing, insulation, electrics, plastering and Building Control.
£850 – £1,200
Per square metre guide for a standard garage conversion shell with mid-range finishes, before shower rooms or kitchenettes.
£9,500 – £14,000
Attached garage converted to living space with insulation, electrics, plastering, decoration and Building Control sign-off.
£12,000 – £17,500
Bedroom or office with en-suite shower room, including plumbing first and second fix.
£14,000 – £22,000
Separate structure with additional services run from the main house. Popular for annex and gym use.
Detached garages often need longer service runs and more extensive thermal upgrades.
Garage slabs below house floor level require careful damp proofing and insulation design.
Steel beams, lintels and opening sizes affect structural costs.
Shower rooms, kitchenettes and premium finishes increase investment proportionally.
Compare like for like: Compare quotations on what's included: Building Control, insulation standards, electrics and decoration should all be in scope.
Most garage conversions are Permitted Development if the footprint does not increase. We verify at survey.
Typically 4–6 weeks for a standard integral conversion, depending on specification.
The internal space converts to living area. We discuss partial conversions and layout at survey if parking matters.
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