Two-storey extensions in St Albans
Need more room in St Albans? Two-storey and first-floor extensions add bedrooms and living space without moving. Here's everything we offer locally.
St Albans at a glance
- Postcode districts
- AL1, AL3 and AL4
- Area
- Hertfordshire, England
- Price region
- East of England
- Nearest towns
- London Colney (2.4 miles), Leverstock Green (4.2 miles), Abbots Langley (4.7 miles), Harpenden (4.7 miles)
- Distance to Watford
- about 7.1 miles
- Approvals
- Two-storey rear: up to 3 m deep and 7 m from the rear boundary under permitted development. Side, wraparound and front: planning permission.
We cover postcode districts AL1, AL3 and AL4 in and around St Albans, along with neighbouring London Colney, Leverstock Green and Abbots Langley.
Extensions available in St Albans
Two-storey rear extensions
St Albans guide price from £57,500, Standard spec.
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Two-storey side extensions
From £88,500 in St Albans. Free visit to firm it up.
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Two-storey wraparound extensions
Guide from £124,000 in St Albans, including VAT.
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Part single, part two-storey extensions
Design, approvals and build for St Albans homes. Guide from £74,000.
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Extensions over a garage
For homes in St Albans: typical guide from £32,500.
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First-floor extensions
Our East of England guide starts at £26,000 for this type.
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Two-storey extensions for semi-detached houses
Our East of England guide starts at £57,500 for this type.
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Two-storey extensions for detached houses
Guide from £88,500 in St Albans, including VAT.
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Kitchen extensions with bedrooms above
Guide from £57,500 (before kitchen units) in St Albans, including VAT.
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Extra bedroom and en-suite extensions
St Albans guide price from £57,500 (plus en-suite), Standard spec.
Learn moreWhich type suits your house?
The boundaries usually decide it. Two-storey work close to a neighbour needs careful design for light and privacy, so at the visit in St Albans we measure distances to every boundary before suggesting a type.
Also available in Hertfordshire
- Two-storey front extensions
- Two-storey extensions for end-of-terrace houses
- Two-storey annexe extensions
- Garage conversions with a room above
- Two-storey extension plans and drawings
- Planning permission for two-storey extensions
- Structural engineering for two-storey extensions
- Building regulations for two-storey extensions
- Party wall notices for extensions
- Design and build two-storey extensions
Rules for St Albans
St Albans is in England. Two-storey rear: up to 3 m deep and 7 m from the rear boundary under permitted development. Side, wraparound and front: planning permission. Householder planning application: £548 (or £575 for applications made from 8 December 2026). Lawful development certificate: £274 (about £288 for applications from 8 December 2026). Councils should decide householder applications within 8 weeks of validation.
The full England rules explained
Questions about extensions in St Albans
Do you cover St Albans?
Yes. We cover St Albans (AL1, AL3 and AL4) and the surrounding area, including London Colney and Leverstock Green. The first site visit is free.
What does a two-storey extension cost in St Albans?
Using our East of England guide, a two-storey rear extension with a 4 m × 3.5 m footprint on two floors (28 m² of new floor space) is about £57,500–£78,000 including VAT. An extension over a garage is about £32,500–£47,500.
Which other places near St Albans do you cover?
Everywhere around it, including London Colney (2.4 miles), Leverstock Green (4.2 miles) and Abbots Langley (4.7 miles), and the rest of Hertfordshire.