House extensions in Letchworth Garden City
From a small utility to a two-storey addition, we take on house extensions throughout Letchworth Garden City, starting with a free visit and a planning check.
- Postcode districtsSG6
- Price regionEast of England (×1.06)
- Planning rulesEngland
- Site visitFree, no obligation
Areas we cover around Letchworth Garden City
Across SG6, we can visit, measure and advise. The same team covers Hitchin (3 miles), Stevenage (5 miles), Welwyn Garden City (12 miles), Harpenden (13 miles), Hertford (14 miles), all within easy reach. Just over the Bedfordshire border, Luton is about 11 miles away.
Do extensions in Letchworth Garden City need planning permission?
In England a single-storey rear extension can usually go up to 3 m beyond the original rear wall of a semi-detached or terraced house, or 4 m on a detached house, without a planning application, provided it is no more than 4 m high, keeps eaves to 3 m within 2 m of a boundary and, with other buildings, covers no more than half the land around the original house. The larger home extension prior approval scheme raises those depths to 6 m and 8 m, with neighbours notified and a 42-day decision.
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.
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).
What extensions cost in Letchworth Garden City
Prices on this page use our East of England factor of ×1.06, include VAT at 20% and cover the build; your written price follows a survey and agreed drawings.
| Extension type | Example size | Standard spec (inc VAT) |
|---|---|---|
| Single-storey rear extensions | 20 m² | £43,000 – £55,500 |
| Conservatory replacement extensions | 14 m² | £31,500 – £41,000 |
| Extensions over a garage | 12 m² | £26,500 – £34,500 |
| Double-storey extensions | 32 m² | £61,000 – £80,000 |
| Kitchen extensions | 20 m² | £44,500 – £56,500 |
| Side return extensions | 11 m² | £27,500 – £35,000 |
| Wraparound extensions | 25 m² | £60,500 – £77,000 |
What works best for Letchworth Garden City houses?
Across the East of England many houses sit on generous plots, and single-storey and wraparound extensions are a natural fit.
Start by comparing wraparound extensions, bungalow extensions and single-storey rear extensions: between them they cover most of the layouts we see requested for houses like these.
Every extension type in Letchworth Garden City
- Extensions over a garage · from £25,000
- Double-storey extensions · from £40,000
- Single-storey rear extensions · from £22,000
- Bedroom extensions · from £27,500
- Annexe extensions · from £58,000
- Side extensions · from £23,000
- Wraparound extensions · from £38,000
- Porch extensions · from £4,200
- Flat roof extensions · from £22,000
- Utility and boot room extensions · from £14,500
- Building regulations for extensions · from £950
- Pitched roof extensions · from £23,500
- Home office extensions · from £16,500
- Orangery extensions · from £31,500
- Side return extensions · from £19,000
- Glass box extensions · from £31,500
- Extension plans and drawings · from £1,250
- Planning permission for extensions · from £350
- Conservatory replacement extensions · from £21,000
- Bungalow extensions · from £27,500
- Kitchen extensions · from £28,500
- Timber frame extensions · from £22,000
Free site visit
A designer visits, takes measurements and photos, and discusses layouts, budget and timing with you.
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
With the design and specification agreed, you get a fixed written price and a start date.
Build and sign-off
Our team builds the extension, keeps you updated weekly and finishes with building control sign-off.
Questions about extensions in Letchworth Garden City
How much does an extension cost in Letchworth Garden City?
Using our East of England factor (×1.06), a standard-spec single-storey extension of 20 m² is a guide £43,000 to £55,500 including VAT, and a 32 m² two-storey extension £61,000 to £80,000. Your written price follows the survey.
How long does an extension take in Letchworth Garden City?
Usually 2 to 4 months of design and approvals, then 10 to 16 weeks on site for a single-storey extension or 16 to 24 weeks for two storeys.
Do I need planning permission for an extension in Letchworth Garden City?
Not always. It depends on the size, position and your property's history. Many single-storey rear extensions in England are permitted development or can use prior approval.
Who do I contract with?
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.
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.