Extensions in St Albans: design, planning and build
From a small utility to a two-storey addition, we take on house extensions throughout St Albans, starting with a free visit and a planning check.
- Postcode districtsAL1, AL2, AL3, AL4
- Price regionEast of England (×1.06)
- Planning rulesEngland
- Site visitFree, no obligation
Which extension suits a St Albans home?
Across the East of England many houses sit on generous plots, and single-storey and wraparound extensions are a natural fit.
The types we would usually look at first for a home in St Albans are wraparound extensions, bungalow extensions and double-storey extensions, depending on the garden and how the house is laid out.
What extensions cost in St Albans
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 |
| Side return extensions | 11 m² | £27,500 – £35,000 |
| Orangery extensions | 16 m² | £47,000 – £59,500 |
| Double-storey extensions | 32 m² | £61,000 – £80,000 |
Planning and building control in St Albans
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).
Covering St Albans and nearby
Across AL1, AL2, AL3, AL4, we can visit, measure and advise. Neighbouring towns we cover include Harpenden (5 miles), Hatfield (5 miles), Hemel Hempstead (5 miles), Welwyn Garden City (6 miles), Borehamwood (7 miles). Just over the Greater London border, Barnet is about 9 miles away.
All extension types we build in St Albans
- Porch extensions · from £4,200
- Timber frame extensions · from £22,000
- Side return extensions · from £19,000
- Annexe extensions · from £58,000
- Pitched roof extensions · from £23,500
- Building regulations for extensions · from £950
- Orangery extensions · from £31,500
- Glass box extensions · from £31,500
- Side extensions · from £23,000
- Bedroom extensions · from £27,500
- Wraparound extensions · from £38,000
- Double-storey extensions · from £40,000
- Single-storey rear extensions · from £22,000
- Extension plans and drawings · from £1,250
- Flat roof extensions · from £22,000
- Conservatory replacement extensions · from £21,000
- Kitchen extensions · from £28,500
- Extensions over a garage · from £25,000
- Planning permission for extensions · from £350
- Utility and boot room extensions · from £14,500
- Home office extensions · from £16,500
- Bungalow extensions · from £27,500
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
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.
Questions about extensions in St Albans
How much does an extension cost in St Albans?
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.
Do you handle building regulations?
Yes. We prepare the drawings and calculations, submit them and book inspections, ending with a completion certificate.
Will my neighbours need to be told?
If you apply for planning or prior approval the council notifies them, and in England party wall notices may be needed for work near a shared boundary.
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.
How long does an extension take in St Albans?
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.
Book a free site visit in St Albans
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.