Side return extensions in Letchworth Garden City
From the first sketch to final sign-off, we plan and build side return extensions in Letchworth Garden City and the surrounding Hertfordshire area.
- Guide price in Letchworth Garden CityFrom £19,000 inc VAT
- PlanningOften permitted development; party wall notice usual
- Build time10–14 weeks on site
- Postcode districtsSG6

Do I need planning permission in Letchworth Garden City?
In England a single-storey side return infill is often permitted development if it stays within the height limits and is no wider than half the width of the original house. Conservation areas, listed buildings and flats always need an application, and the boundary wall usually brings in the Party Wall Act.
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.
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.
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).
Local to Letchworth Garden City
We cover Letchworth Garden City and the postcode districts SG6. 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. Across the East of England many houses sit on generous plots, and single-storey and wraparound extensions are a natural fit.
Guide prices for Letchworth Garden City
Prices below are for Letchworth Garden City, using the East of England factor of ×1.06. They are guide ranges including VAT for the build only, not a quote.
Typical rates in Letchworth Garden City: £2,230 to £4,030 per m² including VAT, depending on specification.
| Size | Essential | Standard | Premium |
|---|---|---|---|
| 1.8 m × 4.5 m 8 m² | £19,000 – £23,000 | £20,000 – £25,500 | £25,000 – £32,500 |
| 2 m × 5.5 m 11 m² | £24,000 – £29,500 | £27,500 – £35,000 | £34,500 – £44,500 |
| 2.2 m × 7 m 15 m² | £33,000 – £40,000 | £38,000 – £48,000 | £47,500 – £60,500 |
Want a range for your exact size? The guide-price tool takes about a minute.
Is a side return extension right for your house?
- Victorian and Edwardian terraces with a rear outrigger
- Narrow galley kitchens
- Homes where the garden is too small to lose much depth
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
It starts with a visit to your house to measure, check access and talk through ideas and budget.
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
We build it with one project manager, book the building control inspections and hand over the completion certificate.
Your questions about a side return extension in Letchworth Garden City
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.
Do you cover all of Letchworth Garden City?
Yes. We cover Letchworth Garden City and the surrounding parts of Hertfordshire. Site visits are free and there is no obligation.
How long does a side return extension take to build in Letchworth Garden City?
On site, typically 10 to 14 weeks once approvals are in place. Before that, allow 6–12 weeks design and approvals.
Do side return extensions need planning permission?
In England many single-storey side returns fit within permitted development if they stay within the height limits and are no wider than half the width of the original house. Conservation areas, listed buildings and flats need an application. Other UK nations have their own rules, which we check.
Will the kitchen be darker?
Not if the roof is designed well. A glazed roof or a line of rooflights along the boundary usually makes the room brighter than before.
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.