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 Portsmouth?
In Portsmouth, a garage conversion typically costs £20,000–£33,500 for a single integral garage, including VAT at 20% (standard rate). That range is adjusted for the South East, where domestic building work typically costs around 12% above the national average. Design, structural calculations and council fees are extra.
| Size or type | Guide range |
|---|---|
| A single integral garage | £20,000–£33,500 |
| Higher specification | £33,500–£42,000 |
The main things that change the cost:
- Bathroom or kitchen
- Heating and flooring
- Foundations under the old door opening
- Single or double garage
A guide range is only a starting point: the guide price tool gives an instant figure for your size, and a free survey turns it into a fixed quote.
Do you need planning permission for a garage conversion in Portsmouth?
The approval route for Portsmouth is set by planning law 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.
At the survey we check your house’s planning history and any restrictions, and tell you which route applies.
What we handle
The work we manage on a garage conversion:
- Electrics, heating and plastering
- Floor raised with insulation and damp-proof membrane
- Planning check for removed permitted development rights
- Drawings and building control application
- New wall and window to replace the garage door
- Foundation check under the garage door opening
How long does it take?
Allow 3 to 6 weeks on site. Before that, surveys, drawings and approvals usually take 6 to 12 weeks, longer if the council asks for changes.
Building in Portsmouth
The South East has a broad mix of housing, from Victorian terraces in the towns to post-war semis and newer estates, so extension types vary street by street.
From PO5 outwards, we take on projects throughout Portsmouth and the surrounding parts of Hampshire.
How it works
- 01
Free visit
We look at the property, talk through what you want and measure up. There is no charge and no obligation.
- 02
Drawings and written quote
We prepare the design and give you a written, itemised quote with inclusions and exclusions.
- 03
Approvals
Planning or permitted development confirmation, building regulations and any party wall matters.
- 04
Build and sign-off
We run the build to a written programme and hand over the completion certificate.
Questions about garage conversions in Portsmouth
How much does a garage conversion cost in Portsmouth?
In Portsmouth, a garage conversion typically costs £20,000–£33,500 for a single integral garage, including VAT at 20% (standard rate). Your fixed price depends on the survey and drawings.
Who approves a garage conversion in Portsmouth?
Planning matters in Portsmouth go to the council covering your address, and the work needs building control approval. We prepare and submit the applications for you.
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.
Will losing the garage affect parking?
Councils sometimes object if on-street parking is under pressure. We check local parking standards.
Can a detached garage be converted?
Yes, but using it as separate living accommodation may need planning permission.