St Albans, Hertfordshire
Two-storey rear extension in St Albans
Two-storey rear extension in St Albans: a larger kitchen downstairs and an extra bedroom or bathroom upstairs, under one roof. We measure the house, show you what the rules allow, price it in writing and build it.
We cover St Albans (AL1 and AL2) as part of our Hertfordshire work. In St Albans, a two-storey rear extension is worth comparing with the cost of moving once stamp duty, agents' and legal fees are counted.
Book a free site visit
Tell us about the house and we'll call to arrange a free, no-obligation visit.
How much does a two-storey rear extension cost in St Albans?
A two-storey rear extension in St Albans is priced at £1,910–£2,860 per square metre including VAT as a guide, before kitchen fit-out and fees. East of England prices run slightly above our West Midlands baseline; clay soils near trees are the main foundation variable.
| Size | Guide price inc VAT |
|---|---|
| 3 m × 5 m footprint, two floors (30 m²) | £57,000–£86,000 |
| 4 m × 6 m footprint, two floors (48 m²) | £91,500–£137,500 |
We put a fixed price in writing once the design is agreed, and explain any provisional sums such as foundations.
Do you need planning permission for a two-storey rear extension in St Albans?
Planning for a two-storey rear extension in St Albans follows the English householder rules.
A two-storey rear extension can be permitted development in England only if it projects no more than 3 metres, stays at least 7 metres from the rear boundary, matches the existing roof pitch and has obscure-glazed upper side windows. In practice most double-storey rear extensions go through a householder planning application.
Conservation areas, National Parks, National Landscapes and the Broads restrict permitted development, and listed buildings always need listed building consent. We check your house's planning history and any conservation area before drawing, so the route is clear before you spend on plans.
What are homes in St Albans like to extend?
St Albans mixes Victorian terraces with 1930s semis, so both side returns and full-width kitchen extensions suit houses here.
How a two-storey rear extension in St Albans comes together
Free site visit
We measure the house and garden, look at the back wall, drainage and boundaries, and talk through what you want from the space.
Drawings and budget
Floor plans and elevations for the options, each with a guide price.
Approvals
Permitted development check, prior approval or planning application, then Building Regulations drawings and structural calculations, plus party wall notices where they apply.
Build and sign-off
We build to the approved drawings with regular updates, then hand over the building control completion certificate and any guarantees from suppliers.
Two-storey rear extensions near St Albans
From St Albans, the nearest places we also cover are Abbots Langley (4.7 miles) and Harpenden (4.7 miles).
- Two-storey rear extension in Abbots Langley
- Two-storey rear extension in Harpenden
- Two-storey rear extension in Hatfield
- Two-storey rear extension in Hemel Hempstead
- Two-storey rear extension in North Watford
Other work in St Albans:
FAQ
Two-storey rear extension questions in St Albans
How long does a rear extension take to build in St Albans?
Most single-storey rear extensions take 10 to 16 weeks on site and two-storey extensions 16 to 26 weeks, after design and approvals.
Will I need a structural engineer?
Yes for the beam over the new opening and usually the foundations; we arrange them and their calculations go to building control.
What is the 45-degree rule?
Many councils check that a two-storey extension does not cross a 45-degree line drawn from the nearest habitable window of the neighbouring house. We test it at the first drawing.
Can you match the brick or stone on my St Albans house?
We source the closest match and show you samples before ordering; reclaimed materials are often the best match on older houses.
Can I live at home while the extension is built?
Usually yes. Most of the work is outside until the back wall is opened near the end, and that stage is screened off.
Who will build my extension?
Vetted building teams working under contract to us. Your contract is with S&K Property Investments and Improvement Ltd for the design and the build.