Extensions over a garage across Berkhamsted
Planning an over-garage extension in Berkhamsted? We survey the house, work out the planning route, draw the design and build it, so you deal with one team from the first visit to the completion certificate.
- Guide price in BerkhamstedFrom £25,000 inc VAT
- PlanningHouseholder application needed
- Build time12–18 weeks on site
- Postcode districtsHP4
Working in Berkhamsted
Postcode districts we cover around Berkhamsted include HP4. The same team covers Hemel Hempstead (5 miles), Rickmansworth (9 miles), Harpenden (10 miles), St Albans (10 miles), all within easy reach.
The East of England mixes market-town terraces, inter-war semis and modern estates. Clay soils are common in parts of the region, which can affect foundation design.
What should I budget for an over-garage extension in Berkhamsted?
For Berkhamsted we adjust our national guide rates by ×1.06, the factor we use for East of England. Figures include VAT; your written quote after the survey replaces them.
Typical rates in Berkhamsted: £1,910 to £3,600 per m² including VAT, depending on specification.
| Size | Essential | Standard | Premium |
|---|---|---|---|
| Over a single garage 12 m² | £25,000 – £31,500 | £26,500 – £34,500 | £34,000 – £43,500 |
| Over a large single garage 16 m² | £30,500 – £37,500 | £35,500 – £46,000 | £45,500 – £58,000 |
| Over a double garage 24 m² | £45,500 – £56,000 | £53,000 – £69,000 | £68,500 – £86,500 |
For a figure based on your own dimensions, use our guide-price tool.
Will the council need to approve it?
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.
Before any drawing is finalised we check whether the house is listed, in a conservation area or subject to an Article 4 direction.
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).
Who an over-garage extension suits
- Homes where the landing can connect to the new room
- Families needing a bedroom without losing garden
- Detached and link-detached houses with an attached garage
Fitting the new room to the existing landing is the planning puzzle inside the house. We design the connection first, then the roof, so the extension does not end up with awkward steps or a corridor through a bedroom.
How the project works
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
It starts with a visit to your house to measure, check access and talk through ideas and budget.
Design and approvals
We draw the design, agree it with you and handle planning or permitted development checks and building regulations.
Fixed written price
We confirm the build price in writing, based on the approved drawings and the finishes you have chosen.
Build and sign-off
Work is carried out to the agreed programme, inspected by building control and signed off at the end.
Your questions about an over-garage extension in Berkhamsted
How long does an over-garage extension take to build in Berkhamsted?
On site, typically 12 to 18 weeks once approvals are in place. Before that, allow 8–14 weeks design and approvals.
Do you cover all of Berkhamsted?
Yes. We cover Berkhamsted and the surrounding parts of Hertfordshire. Site visits are free and there is no obligation.
Will my neighbours in Berkhamsted be involved?
If a planning application or prior approval is needed, the council notifies neighbours. If the work is on or near a shared boundary, party wall notices may also be needed.
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.
How much does a room over a garage cost?
Our guide range is about £1,910 to £3,600 per m² including VAT. A single-garage room of about 12 m² usually costs £26,500 to £34,500 at standard spec, more if the garage needs rebuilding.
Book a free site visit in Berkhamsted
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.