Two-storey extensions in Forest Hill
We design, get approval for and build two-storey extensions in Forest Hill and the surrounding area. Choose the type of extension below or book a free site visit.
Forest Hill at a glance
- Postcode districts
- SE23
- Area
- Greater London, England
- Price region
- London
- Nearest towns
- Crofton Park (0.5 miles), Lewisham (0.9 miles), Catford (0.9 miles), Ladywell (1 mile)
- 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 Forest Hill we also work in Crofton Park, Lewisham and Catford, and across the rest of Greater London. Postcode district in and near Forest Hill: SE23.
Extensions available in Forest Hill
Two-storey rear extensions
Design, approvals and build for Forest Hill homes. Guide from £67,000.
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Two-storey side extensions
Guide from £103,500 in Forest Hill, including VAT.
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Two-storey wraparound extensions
Guide from £144,500 in Forest Hill, including VAT.
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Part single, part two-storey extensions
Design, approvals and build for Forest Hill homes. Guide from £86,500.
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Extensions over a garage
Design, approvals and build for Forest Hill homes. Guide from £38,000.
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First-floor extensions
Our London guide starts at £30,000 for this type.
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Two-storey extensions for semi-detached houses
For homes in Forest Hill: typical guide from £67,000.
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Two-storey extensions for detached houses
From £103,500 in Forest Hill. Free visit to firm it up.
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Kitchen extensions with bedrooms above
Guide from £67,000 (before kitchen units) in Forest Hill, including VAT.
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Extra bedroom and en-suite extensions
Guide from £67,000 (plus en-suite) in Forest Hill, including VAT.
Learn moreWhich type suits your house?
Which type suits your house in Forest Hill depends mostly on where you have room. A deep garden points to a rear extension; space beside the house points to a side or over-garage extension; a house that already has a single-storey extension can often take a first floor on top.
Also available in Greater London
- 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 Forest Hill
Forest Hill 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 Forest Hill
Do you cover Forest Hill?
Yes. We cover Forest Hill (SE23) and the surrounding area, including Crofton Park and Lewisham. The first site visit is free.
What does a two-storey extension cost in Forest Hill?
Using our London 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 £67,000–£90,500 including VAT. An extension over a garage is about £38,000–£55,000.
Which other places near Forest Hill do you cover?
Everywhere around it, including Crofton Park (0.5 miles), Lewisham (0.9 miles) and Catford (0.9 miles), and the rest of Greater London.