St Helens over-garage extensions, designed and built
If you live in St Helens and want more space without moving, an over-garage extension is one of the most practical ways to get it. We handle the drawings, approvals and the build.
- Guide price in St HelensFrom £22,500 inc VAT
- PlanningHouseholder application needed
- Build time12–18 weeks on site
- Postcode districtsL34, L35, WA9, WA10, WA11
What should I budget for an over-garage extension in St Helens?
These guide figures apply our North West England adjustment (×0.95) to national rates. They include VAT at 20% and cover the build itself; design and council fees are listed separately.
Typical rates in St Helens: £1,710 to £3,230 per m² including VAT, depending on specification.
| Size | Essential | Standard | Premium |
|---|---|---|---|
| Over a single garage 12 m² | £22,500 – £28,000 | £23,500 – £31,000 | £30,500 – £39,000 |
| Over a large single garage 16 m² | £27,000 – £33,500 | £31,500 – £41,500 | £41,000 – £52,000 |
| Over a double garage 24 m² | £41,000 – £50,500 | £47,500 – £62,000 | £61,500 – £78,000 |
Try the guide-price tool to see a range for your own size and finish.
Working in St Helens
Across L34, L35, WA9, WA10, WA11, WA12, we can visit, measure and advise. The same team covers Prescot (3 miles), Huyton (5 miles), Newton-le-Willows (5 miles), Golborne (6 miles), all within easy reach.
For homes towards Greater Manchester, Ashton-in-Makerfield is around 4 miles away. Across the North West, terraced houses with small rear yards suit compact rear and side return extensions, while suburban semis have room for more.
Planning rules that apply in St Helens
In England any side extension over one storey, including a room built over a side garage, needs a householder planning application. The fee is £548 from 1 April 2026 and councils aim to decide within 8 weeks.
Homes in conservation areas, national parks, National Landscapes (formerly AONBs), the Broads and World Heritage Sites have tighter rules, so we always check the property's status and planning history before design starts.
Building over or within 3 m of a public sewer needs the water company's consent, usually through a build-over agreement, before the foundations go in.
If the work involves a shared wall, building on the boundary, or digging foundations within 3 m (sometimes 6 m) of a neighbour's building, the Party Wall etc. Act 1996 applies and notice must be served before work starts: two months for work to a party wall, one month for new walls on the boundary and for excavations.
Applications are decided by the local planning authority (your district, borough or unitary council).
Included in a typical project
- New floor structure, walls and roof
- Insulation, electrics, heating and finish
- Design and householder planning application
- Opening into the existing first floor
- Strengthening or rebuilding the garage walls if needed
From first visit to completion
Site visits are free and there is no obligation. Where drawings are needed, the design stage is priced in writing before it starts.
Free site visit
First, a site visit: we look at the house, garden, access and drains and listen to what you need.
Design and approvals
Once the layout is agreed, we deal with the council: planning permission or written confirmation that none is needed, plus building control.
Fixed written price
You receive a written, itemised price and programme. Nothing starts until you are happy with it.
Build and sign-off
Our team builds the extension, keeps you updated weekly and finishes with building control sign-off.
Common questions in St Helens
Do you cover all of St Helens?
Yes. We cover St Helens and the surrounding parts of Merseyside. Site visits are free and there is no obligation.
Can I see a price before committing to anything?
Yes. The guide prices on this page are adjusted for St Helens, and the guide-price tool gives a range for your own size. After the survey you get a written price before anything is agreed.
How long does an over-garage extension take to build in St Helens?
On site, typically 12 to 18 weeks once approvals are in place. Before that, allow 8–14 weeks design and approvals.
How much does a room over a garage cost?
Our guide range is about £1,710 to £3,230 per m² including VAT. A single-garage room of about 12 m² usually costs £23,500 to £31,000 at standard spec, more if the garage needs rebuilding.
Can I keep using the garage during the build?
Usually not for parking. The garage roof is removed and the space below is used for access and props for part of the build.
Book a free site visit in St Helens
We will measure up, check the planning position and give you honest guide figures.
- Free, no-obligation site visit
- Planning route checked before you spend on drawings
- Written price once the design is agreed
- Building control sign-off at the end
Prefer to talk? Call 0800 088 6341 or .
Book a free site visit
Tell us a little about the project and we will arrange a time.