Thinking about extending your home in Lewisham, London SE13? With its growing appeal, excellent transport links, and a mix of Victorian terraces, post-war homes, and modern developments, Lewisham is one of South East London’s most exciting places for home improvement. From the Hither Green conservation area to Ladywell, Catford, and the town centre regeneration zone, well-designed home extensions are adding serious space and value to properties across the borough.
This guide is written specifically for Lewisham homeowners — whether you’re based near Hither Green Lane, Lewisham Park, or Ladywell Fields — who want clear and realistic cost expectations, planning guidance, and insight into how Buildaway delivers high-quality extensions with transparent pricing and an 18-month labour warranty.
How Much Does a House Extension Cost in Lewisham (2025)?
Lewisham’s pricing sits close to the South East London average — competitive compared with inner London but reflecting the area’s rising popularity and strong property values. Below are 2025 realistic ranges:
Single-Storey Rear Extension
- Build-only: £2,200 – £2,800 per m²
- Fully finished with kitchen: £2,800 – £3,500 per m²
- Example: 25 m² kitchen-diner = £55,000 – £70,000 build-only or £70,000 – £90,000 turnkey.
Double-Storey Rear Extension
- Build-only: £2,000 – £2,600 per m²
- Fully finished: £2,600 – £3,300 per m²
- Example: 40 m² over two floors = £80,000 – £110,000 build-only or £105,000 – £130,000 turnkey.
Side Return & Wrap-Around Extensions
Typically priced in line with single-storey builds: £2,200 – £2,900 per m², depending on structure and glazing.
These reflect Lewisham’s mid-market construction rates for compliant, Building Control-approved extensions by reliable, insured contractors.
What Drives the Price Up or Down
- Property age – many Lewisham terraces and 1930s semis need upgraded foundations or steelwork.
- Roof type & glazing – simple flat roofs are economical; roof lanterns or large bifold doors add £3k–£8k+.
- Kitchens & bathrooms – kitchens £10k–£25k+, bathrooms £6k–£15k+.
- Ground conditions – older properties near Ladywell Fields or the Ravensbourne River may require drainage enhancements.
- Access & parking – limited parking on narrow streets like those off Hither Green Lane can slightly extend timelines.
- Planning restrictions – conservation areas like Culverley Green and Hither Green have stricter guidelines.
Planning Permission & Building Control in Lewisham
- Permitted Development (PD): Many single-storey extensions are PD-compliant if within size and height limits.
- Full Planning Permission: Required for double-storey, wrap-around, or front-facing builds.
- Conservation Areas: Culverley Green, Hither Green, and parts of Ladywell require special consideration.
- Building Control: Mandatory for all structure, insulation, drainage, and electrical works.
Buildaway regularly liaises with Lewisham Council’s planning team and private inspectors to ensure smooth applications, compliance, and fully certified project completions.
How Long Will It Take?
- Design & planning: 4–12 weeks (longer for full planning)
- Technical drawings & approvals: 2–6 weeks
- On-site build:
- Single-storey: 10–14 weeks
- Double-storey: 14–20 weeks
- Add additional time for bespoke kitchens, custom glazing, or complex access.
Typical Full Project Budget Breakdown (30 m² Double-Storey)
| Element | Typical Cost |
|---|---|
| Core structure & shell | £70,000 – £85,000 |
| Windows / doors / glazing | £5,000 – £10,000 |
| Kitchen supply & fit | £12,000 – £25,000 |
| Bathroom fit-out | £6,000 – £12,000 |
| Heating / boiler / Megaflo | £3,000 – £5,000 |
| Flooring & decorating | £5,000 – £15,000 |
| Professional fees & permissions | £3,000 – £8,000 |
| Total realistic range: | £100,000 – £135,000 |
(High-spec or conservation builds can exceed £150k.)
Why Lewisham Clients Choose Buildaway
- Proven local expertise — experience across Lewisham, Catford, and Hither Green homes.
- Transparent quoting — clear, itemised quotes with no hidden extras.
- 18-month workmanship warranty — extended guarantee for total confidence.
- Fully insured & certified — Gas Safe, NICEIC, and public liability cover.
- End-to-end management — from design through planning and construction.
Frequently Asked Questions
Do I need planning permission for my Lewisham extension?
Not always — single-storey rears often qualify under PD, but double-storey or conservation properties will need approval.
Can I live in my property during construction?
Yes, especially for single-storey projects. Buildaway ensures safe and secure working environments.
Will I need to upgrade my boiler or heating system?
If you’re adding bathrooms or large kitchen areas, a Megaflo or modern boiler is recommended.
What warranty do you provide?
Buildaway provides an 18-month labour warranty on all structural and finishing works.
Next Steps for Lewisham Homeowners
If you’re planning a home extension in Lewisham, Hither Green, or Ladywell:
- Book a free home consultation to discuss your design and budget.
- Buildaway can handle design, planning, and full build delivery.
- Receive a transparent, itemised quote with realistic timescales.
📞 020 8108 0388 📧 info@buildaway.co.uk
Buildaway — trusted by Lewisham homeowners for compliant, high-quality extensions that enhance comfort, value, and modern living.