Two-storey extensions in Windsor
Everything for a two-storey extension in Windsor, in one place: types, guide prices for South East England, the approval rules in England and how to get started.
Windsor at a glance
- Postcode districts
- SL4
- Area
- Berkshire, England
- Price region
- South East England
- Nearest towns
- Slough (1.8 miles), Egham (4.1 miles), Burnham (4.6 miles), Staines (5.4 miles)
- Distance to Reading
- about 16.1 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.
Windsor sits about 16.1 miles from Reading. Closer to home, Slough is 1.8 miles away and Egham 4.1 miles.
Extensions available in Windsor
Two-storey rear extensions
Guide from £61,500 in Windsor, including VAT.
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Two-storey side extensions
Windsor guide price from £94,500, Standard spec.
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Two-storey wraparound extensions
For homes in Windsor: typical guide from £132,500.
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Part single, part two-storey extensions
Guide from £79,000 in Windsor, including VAT.
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Extensions over a garage
Our South East England guide starts at £34,500 for this type.
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First-floor extensions
Our South East England guide starts at £27,500 for this type.
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Two-storey extensions for semi-detached houses
Windsor guide price from £61,500, Standard spec.
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Two-storey extensions for detached houses
Our South East England guide starts at £94,500 for this type.
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Kitchen extensions with bedrooms above
Windsor guide price from £61,500 (before kitchen units), Standard spec.
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Extra bedroom and en-suite extensions
From £61,500 (plus en-suite) in Windsor. Free visit to firm it up.
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 Windsor we measure distances to every boundary before suggesting a type.
Also available in Berkshire
- 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 Windsor
Windsor 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 Windsor
Do you cover Windsor?
Yes. We cover Windsor (SL4) and the surrounding area, including Slough and Egham. The first site visit is free.
What does a two-storey extension cost in Windsor?
Using our South East 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 £61,500–£83,000 including VAT. An extension over a garage is about £34,500–£50,500.
Which other places near Windsor do you cover?
Everywhere around it, including Slough (1.8 miles), Egham (4.1 miles) and Burnham (4.6 miles), and the rest of Berkshire.