Two-storey extensions in Cosham
Everything for a two-storey extension in Cosham, in one place: types, guide prices for South East England, the approval rules in England and how to get started.
Cosham at a glance
- Postcode districts
- PO6
- Area
- Hampshire, England
- Price region
- South East England
- Nearest towns
- Waterlooville (2.8 miles), Havant (3.5 miles), Portsmouth (3.5 miles), Southsea (4.5 miles)
- Distance to Southampton
- about 15.4 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.
Around Cosham we also work in Waterlooville, Havant and Portsmouth, and across the rest of Hampshire. Postcode district in and near Cosham: PO6.
Extensions available in Cosham
Two-storey rear extensions
Our South East England guide starts at £61,500 for this type.
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Two-storey side extensions
Guide from £94,500 in Cosham, including VAT.
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Two-storey wraparound extensions
Guide from £132,500 in Cosham, including VAT.
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Part single, part two-storey extensions
Our South East England guide starts at £79,000 for this type.
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Extensions over a garage
From £34,500 in Cosham. Free visit to firm it up.
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First-floor extensions
Guide from £27,500 in Cosham, including VAT.
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Two-storey extensions for semi-detached houses
Cosham guide price from £61,500, Standard spec.
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Two-storey extensions for detached houses
From £94,500 in Cosham. Free visit to firm it up.
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Kitchen extensions with bedrooms above
For homes in Cosham: typical guide from £61,500 (before kitchen units).
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Extra bedroom and en-suite extensions
Design, approvals and build for Cosham homes. Guide from £61,500 (plus en-suite).
Learn moreWhich type suits your house?
Rear, side, wraparound or over the garage: each adds space in a different way. For most houses in Hampshire, one or two of these will clearly suit the plot better than the rest, and we'll tell you which.
Also available in Hampshire
- 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 Cosham
Cosham 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 Cosham
Do you cover Cosham?
Yes. We cover Cosham (PO6) and the surrounding area, including Waterlooville and Havant. The first site visit is free.
What does a two-storey extension cost in Cosham?
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 Cosham do you cover?
Everywhere around it, including Waterlooville (2.8 miles), Havant (3.5 miles) and Portsmouth (3.5 miles), and the rest of Hampshire.