Planning to extend your home in Orpington (BR5, BR6)? Located on the edge of Greater London, Orpington offers a rare balance — more space, excellent schools, and easy commuter access into the city. With property values rising in sought-after areas like Chelsfield, Petts Wood, and Crofton, many homeowners are choosing to extend rather than move. Whether it’s a single-storey kitchen-diner overlooking your garden, a wrap-around side return, or a double-storey extension for more bedrooms, understanding the true cost of an Orpington extension in 2025 will help you plan smartly.
This guide is tailored for Orpington homeowners — from Green Street Green and Farnborough Village to St Mary Cray and Petts Wood — who want accurate 2025 cost insights, planning advice, and local expertise. It’s built on Buildaway’s real experience delivering high-quality extensions across the South East, backed by transparent pricing and an 18-month labour warranty.
How Much Does a House Extension Cost in Orpington (2025)?
Orpington sits in a mid-to-upper South East London market bracket — generally more affordable than inner London but higher than Kent towns further out. Below are realistic 2025 price ranges:
Single-Storey Rear Extension
- Build-only: £2,200 – £2,800 per m²
- Fully finished with kitchen: £2,800 – £3,500 per m²
- Example: a 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 reflect fair mid-market Orpington prices — typical of reputable builders meeting Building Control standards and providing full aftercare.
What Drives the Price Up or Down
- Size & design complexity – bigger or bespoke layouts mean higher costs.
- Structural steel (RSJs) – removing load-bearing walls adds £2k–£6k+.
- Ground & drainage conditions – Orpington’s clay-heavy soil or drain rerouting can raise costs.
- Roof & glazing choices – skylight flat roofs are cost-effective; bifold/sliding doors add £3k–£8k+.
- Kitchen & bathroom fittings – kitchens £10k–£25k+, bathrooms £6k–£15k+.
- Heating & plumbing upgrades – Megaflo/unvented cylinder if adding bathrooms (£2.5k–£4.5k).
- Finishes & joinery – flooring, carpentry, and decorating.
- Site access & parking – narrow residential streets near Orpington High Street or Green Street Green can impact skip and labour costs.
Planning Permission & Building Control in Orpington
- Permitted Development (PD): Many single-storey rear or side extensions qualify under PD rights if within size limits.
- Planning permission: Required for double-storey, wrap-around, or front extensions.
- Conservation Areas: Properties near Knoll Rise or Chelsfield Park may have Article 4 restrictions removing PD rights.
- Building Control: Mandatory for structure, insulation, drainage, and electrical works.
Buildaway works closely with Bromley Council and approved inspectors to ensure full compliance and smooth approvals.
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 custom 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 realistic range: | £100,000 – £135,000 |
(Higher-spec finishes or larger extensions can exceed £150k.)
Why Orpington Clients Choose Buildaway
- Local expertise — we understand Orpington’s housing stock, from 1930s semis to post-war family homes.
- Transparent quoting — clear itemised pricing, no hidden extras.
- 18-month labour warranty — longer than most mid-market builders.
- Fully insured & certified — Gas Safe, NICEIC, and liability cover.
- Smooth project management — clear communication, scheduling, and compliance from start to finish.
Frequently Asked Questions
Do I need planning permission for my Orpington extension?
Not usually for single-storey within PD limits, but always for double-storey, front, or conservation area homes.
Can I live at home during the build?
Yes, particularly for single-storey projects — disruption is manageable with temporary kitchen setups.
Will I need to upgrade my heating system?
If you’re adding bathrooms or expanding kitchen space, a Megaflo or boiler upgrade is advisable.
What guarantees do you provide?
Buildaway provides an 18-month labour warranty on all work.
Next Steps for Orpington Homeowners
If you’re ready to explore extending your Orpington home:
- Book a free home visit to review your space and discuss design ideas.
- Buildaway can help with architectural design, planning, and structural drawings.
- You’ll receive a transparent, itemised quotation with no hidden extras.
📞 020 8108 0388 📧 info@buildaway.co.uk
Buildaway — trusted by Orpington homeowners for high-quality extensions, kitchens, and full home transformations.