Extensions over a garage for homes in Letchworth Garden City
A over-garage extension in Letchworth Garden City starts with the right design and the right approval route. We take care of both, then build it with our own project management.
- Guide price in Letchworth Garden CityFrom £25,000 inc VAT
- PlanningHouseholder application needed
- Build time12–18 weeks on site
- Postcode districtsSG6
Guide prices for Letchworth Garden City
These guide figures apply our East of England adjustment (×1.06) to national rates. They include VAT at 20% and cover the build itself; design and council fees are listed separately.
Typical rates in Letchworth Garden City: £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 |
Want a range for your exact size? The guide-price tool takes about a minute.
Extensions in and around Letchworth Garden City
Across SG6, we can visit, measure and advise. Nearby, we also take on projects in Hitchin (3 miles), Stevenage (5 miles), Welwyn Garden City (12 miles), Harpenden (13 miles).
Luton, in Bedfordshire, is roughly 11 miles from Letchworth Garden City and also on our list. 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.
Included in a typical project
- Strengthening or rebuilding the garage walls if needed
- Structural survey of garage walls and foundations
- Opening into the existing first floor
- Insulation, electrics, heating and finish
- Design and householder planning application
Do I need planning permission in Letchworth Garden City?
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.
The planning position for a specific Letchworth Garden City address depends on its history and any designations, which is why we check it at the first visit.
Building regulations approval is separate from planning. In England you can use the council's building control team or a registered building control approver; a full plans application gets the drawings checked before work starts, and the inspector signs the work off with a completion certificate.
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.
Applications are decided by the local planning authority (your district, borough or unitary council).
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
First, a site visit: we look at the house, garden, access and drains and listen to what you need.
Design and approvals
Drawings are prepared and agreed with you, then submitted for the right planning route and building regulations approval.
Fixed written price
The price is fixed in writing once the design is settled, with a clear programme and payment stages.
Build and sign-off
Work is carried out to the agreed programme, inspected by building control and signed off at the end.
Over-garage extension questions answered
How long does an over-garage extension take to build in Letchworth Garden City?
On site, typically 12 to 18 weeks once approvals are in place. Before that, allow 8–14 weeks design and approvals.
Will my neighbours in Letchworth Garden City 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.
Who do I contract with for an over-garage extension in Letchworth Garden City?
Your contract is with S&K Property Investments and Improvement Ltd, which designs and manages the project and the build teams who carry it out.
Can my garage take the weight of a room on top?
Some can and some cannot. Many garages have a single-skin wall or shallow foundations. Our structural engineer checks this before we give a fixed price.
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 Letchworth Garden City
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.