Side extensions across Letchworth Garden City
A side 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 £23,000 inc VAT
- PlanningSingle storey can be permitted development
- Build time10–18 weeks on site
- Postcode districtsSG6
Side extension prices in 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: £1,860 to £3,600 per m² including VAT, depending on specification.
| Size | Essential | Standard | Premium |
|---|---|---|---|
| 2.5 m × 5 m 12 m² | £23,000 – £28,000 | £26,000 – £34,000 | £33,000 – £43,500 |
| 3 m × 6 m 18 m² | £33,000 – £40,500 | £39,000 – £51,000 | £49,500 – £65,000 |
| 3 m × 8 m 24 m² | £44,500 – £53,500 | £52,000 – £67,500 | £66,000 – £86,500 |
For a figure based on your own dimensions, use our guide-price tool.
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).
Just over the Bedfordshire border, Luton is about 11 miles away. 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.
Planning rules that apply in Letchworth Garden City
In England a single-storey side extension can be permitted development if it is no more than 4 m high and no wider than half the width of the original house. Two-storey side extensions, and any side extension on designated land such as a conservation area, need a householder planning application.
In a conservation area, national park, National Landscape, the Broads or a World Heritage Site the permitted development limits are tighter (no side or two-storey extensions without an application). Listed homes need listed building consent, and if permitted development rights have been removed, any extension needs an application.
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.
Applications are decided by the local planning authority (your district, borough or unitary council).
Who a side extension suits
- Detached and semi-detached houses with side land
- Houses where the rear garden is small
- Homes needing a utility, study or ground-floor bedroom
Our process, step by step
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
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 Letchworth Garden City
Who do I contract with for a side 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.
How long does a side extension take to build in Letchworth Garden City?
On site, typically 10 to 18 weeks once approvals are in place. Before that, allow 6–14 weeks design and approvals.
Can I see a price before committing to anything?
Yes. The guide prices on this page are adjusted for Letchworth Garden City, 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 much does a side extension cost?
Our guide range is about £1,860 to £3,600 per m² including VAT, depending on specification, so a standard 18 m² single-storey side extension lands around £39,000 to £51,000 in Letchworth Garden City.
Can I build a side extension without planning permission?
In England a single-storey side extension can be permitted development if it is no more than 4 m high and no wider than half the width of the original house. Two-storey side extensions, and any side extension on designated land such as a conservation area, need a planning application.
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.