Garage Conversion Cost in London (2026 Edition)

Converting a garage is typically one of the most cost-effective ways to add liveable space to a London property. You've already got the walls, the foundation, and the roof. But how much does it actually cost to turn a cold, dusty dumping ground into a warm, modern room in 2026?

I'll be straight with you: turning a garage into a habitable space isn't just about throwing down some carpet and painting the walls. To do it right—and legally—requires proper insulation, damp proofing, and bringing the structure up to current building regulations.

Average Garage Conversion Costs (2026)

Here’s what you should budget for a standard single-garage conversion in London. This assumes a standard brick-built garage being converted into a home office, playroom, or extra bedroom.

What Drives the Price Up?

• Structural Condition: If the existing foundations are too shallow, or the roof needs totally replacing rather than just insulating, costs rise fast.
• Plumbing and Electrics: Want a shower room or utility space out there? Digging trenches for new soil pipes will add £2,000+ to the bill.
• Windows and Doors: Replacing the up-and-over door with matching brickwork and a high-spec window is standard, but adding bi-fold doors or skylights adds a premium.

Do You Need Planning Permission?

In most cases, an internal garage conversion falls under Permitted Development, meaning no formal planning permission is required. However, if you're altering the exterior look of a conservation area property, or if your home has "covenants" restricting garage alterations (common in newer builds), you will need to apply.