Thinking about extending your home in Eltham (SE9)? This popular South East London suburb, part of the Royal Borough of Greenwich, blends 1930s semis, post-war terraces, and modern developments around Avery Hill Park with historic properties near Eltham Palace. With families drawn to good schools and green spaces, demand for larger, modernised homes is strong. A well-planned extension — whether an open-plan kitchen-diner, a side return to brighten a Victorian terrace, or a double-storey rear for extra bedrooms — is one of the smartest ways to create space and boost value.
This guide is tailored for Eltham homeowners — from New Eltham and Mottingham to Middle Park and Falconwood — who want accurate 2025 pricing, planning advice, and trusted local insight. It’s based on current South East London rates and Buildaway’s proven expertise, backed by transparent quotes and an 18-month labour warranty.
How Much Does a House Extension Cost in Eltham (2025)?
Eltham falls into a mid-London market bracket: not as expensive as central London but higher than Kent suburbs further out. Here are the 2025 averages:
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
Comparable to single-storey rates: £2,200 – £2,900 per m², depending on structure and glazing.
These figures are realistic for quality contractors who comply with Building Control, provide insurance, and offer full aftercare.
What Drives the Price Up or Down
- Size & footprint – bigger = more foundations, roof, insulation, labour.
- Steel (RSJs) – removing structural walls adds £2k–£6k+.
- Ground & drainage – weak soil or moving drains increases cost.
- Roof & glazing – skylight flat roofs are cheaper; bifolds/sliding doors add £3k–£8k+.
- Kitchens & bathrooms – kitchens £10k–£25k+, bathrooms £6k–£15k+.
- Plumbing & heating – Megaflo/unvented cylinder for extra bathrooms £2.5k–£4.5k.
- Finishes & joinery – flooring, carpentry, decorating push up costs.
- Access & parking – tricky access on Eltham’s crescents or busier commuter streets can increase labour/skip hire fees.
Planning Permission & Building Control in Eltham
- Permitted Development (PD): Many single-storey rear/side extensions qualify if within limits.
- Full planning permission: Always required for double-storey, front, or wrap-around designs.
- Conservation Areas: Eltham has protected zones — e.g., near Eltham Palace & Progress Estate — where PD rights are restricted.
- Building Control: Always needed for structure, insulation, drainage, and electrics.
Buildaway works closely with Greenwich Council and architects to manage drawings, calculations, and planning submissions.
How Long Will It Take?
- Design & planning: 4–12 weeks
- Technical drawings & approvals: 2–6 weeks
- On-site build:
- Single-storey: 10–14 weeks
- Double-storey: 14–20 weeks
- Add time for bespoke glazing, kitchens, or landscaping.
Typical Full Project Budget Breakdown (30 m² Double-Storey)
| Element | Typical Cost |
|---|---|
| Core structure & shell | £70,000 – £85,000 |
| Windows / 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 range: | £100,000 – £135,000 |
(Custom finishes can push beyond £150k).
Why Eltham Clients Choose Buildaway
- Local expertise — familiar with Eltham housing stock, from 1930s semis to Progress Estate homes.
- Transparent pricing — staged payments with no hidden extras.
- 18-month labour warranty — above the industry average.
- Fully insured & compliant — Gas Safe, NICEIC, liability cover.
- Trusted project management — smooth handling of schedules, neighbours, and Building Control.
Frequently Asked Questions
Do I need planning permission for my Eltham extension?
Often not for single-storey PD projects, but always for double-storey, wrap-arounds, or homes in conservation areas.
Can I live at home while the work is done?
Yes, especially for single-storey projects. Expect disruption, but temporary kitchens help.
Will I need to upgrade my boiler?
Likely if adding bathrooms — an unvented cylinder or new boiler is recommended.
What guarantees do you provide?
Buildaway provides an 18-month labour warranty on all works.
Next Steps for Eltham Homeowners
If you’re considering a home extension in Eltham:
- Book a free home visit to assess your project.
- We can help with design, planning, and structural drawings.
- Receive a clear, itemised quotation with no hidden extras.
📞 020 8108 0388
📧 info@buildaway.co.uk
Buildaway — trusted by Eltham homeowners for extensions, kitchens, and bathrooms done right.