What is a garage conversion?
A garage conversion turns an integral or attached garage into habitable space, such as a study, playroom, bedroom or utility. The garage door is replaced with a wall and window, the floor is raised and insulated, and the walls and roof are brought up to building regulations.
How much does a garage conversion cost in Harrow?
In Harrow, a garage conversion typically costs £23,500–£39,000 for a single integral garage, including VAT at 20% (standard rate). That range is adjusted for London, where domestic building work typically costs around 30% above the national average. Design, structural calculations and council fees are extra.
| Size or type | Guide range |
|---|---|
| A single integral garage | £23,500–£39,000 |
| Higher specification | £39,000–£49,000 |
The main things that change the cost:
- Integral, attached or detached
- Bathroom or kitchen
- Foundations under the old door opening
- Single or double garage
For a figure based on your own measurements, try the guide price tool, then book a free home visit for a fixed quote.
Do you need planning permission for a garage conversion in Harrow?
Here is how the rules work for a garage conversion in England. In England converting an integral or attached garage usually does not need planning permission, unless a condition on the house removed permitted development rights (common on estates built in recent decades) or the house is listed. Building regulations approval is always needed.
Building regulations approval comes from the council’s building control service or a registered building control approver. The work is inspected at key stages, such as foundations, drainage and insulation, and a completion certificate is issued at the end.
Our first visit includes a check of your planning history, so you know the route before paying for drawings.
What we handle
The work we manage on a garage conversion:
- New wall and window to replace the garage door
- Building control completion
- Drawings and building control application
- Floor raised with insulation and damp-proof membrane
- Wall and ceiling insulation
- Foundation check under the garage door opening
How long does it take?
The build itself usually takes 3 to 6 weeks on site. Allow time beforehand for drawings and approvals, usually 6 to 12 weeks.
Building in Harrow
Many London boroughs have conservation areas and detailed design guides, so early design advice saves time at the planning stage.
Our Harrow coverage includes postcode districts HA2, and we also work in nearby places such as Wembley, Pinner and Northolt.
How it works
- 01
Visit and measured survey
A free visit to understand the project, check access and take measurements.
- 02
Drawings and written quote
We prepare the design and give you a written, itemised quote with inclusions and exclusions.
- 03
Permissions sorted
Applications, building control and neighbour arrangements, all before the start date.
- 04
Build and handover
Work follows the agreed programme, with inspections along the way and a completion certificate at the end.
Questions about garage conversions in Harrow
Can a detached garage be converted?
Yes, but using it as separate living accommodation may need planning permission.
Do I need building regulations approval?
Yes. Converting a garage to a habitable room needs building control approval for insulation, ventilation, fire safety and the new wall.
How much does a garage conversion cost in Harrow?
In Harrow, a garage conversion typically costs £23,500–£39,000 for a single integral garage, including VAT at 20% (standard rate). Your fixed price depends on the survey and drawings.
How long does a garage conversion take in Harrow?
Typically 3 to 6 weeks on site. Design and approvals beforehand usually take 6 to 12 weeks.
Do I need planning permission for a garage conversion?
Usually not if the work is internal and the house keeps its permitted development rights. Many newer houses have planning conditions that remove those rights, in which case an application is needed.