Thinking about extending your home in Dulwich, London SE21? With its elegant period homes, tree-lined avenues, and conservation areas, Dulwich remains one of South London’s most desirable and architecturally sensitive locations. From the leafy roads of Dulwich Village and Lordship Lane to the characterful streets of West Dulwich and East Dulwich, a high-quality home extension can unlock new space and elevate property value — while preserving the charm that makes the area so special.
This guide is designed specifically for Dulwich homeowners — whether you’re near Dulwich College, Belair Park, or North Cross Road — who want to understand realistic 2025 extension costs, planning regulations, and how to choose a trusted local builder. It draws on Buildaway’s extensive South East London experience, delivering transparent quotes, full compliance, and an 18-month workmanship warranty.
How Much Does a House Extension Cost in Dulwich (2025)?
Dulwich sits in a premium South East London price bracket, reflecting the area’s high-quality housing stock, conservation constraints, and design expectations. Below are the typical price ranges for 2025 based on Buildaway’s experience.
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
Usually aligned with single-storey costs: £2,200 – £2,900 per m², depending on roof glazing and internal layout.
These figures represent the realistic market rates for Dulwich and its surrounding SE21–SE22 postcodes, balancing quality craftsmanship with full Building Control compliance.
What Drives the Price Up or Down
- Conservation area constraints – much of Dulwich is under conservation protection (e.g., Dulwich Village Conservation Area), meaning specific materials and designs are required.
- Property type – many homes are Georgian or Victorian, requiring sympathetic structural work.
- Roof style & glazing – flat roofs with skylights are cost-effective; heritage-style roof lanterns or steel doors add £3k–£8k+.
- Kitchens & bathrooms – kitchens typically £10k–£25k+, bathrooms £6k–£15k+.
- Drainage & ground conditions – some roads near Belair Park and Croxted Road may need improved drainage.
- Access & parking – narrow village lanes and resident parking schemes can affect site logistics.
- Finishes & joinery – bespoke carpentry, sash windows, and heritage finishes increase cost but also value.
Planning Permission & Building Control in Dulwich
- Permitted Development (PD): Many single-storey extensions qualify, but must meet limits on height and projection.
- Full Planning Permission: Required for double-storey, front, or wrap-around extensions — especially in conservation zones.
- Conservation Areas: Dulwich Village, East Dulwich, and West Dulwich each have separate planning considerations.
- Building Control: Always needed for structural integrity, insulation, plumbing, and electrics.
Buildaway works closely with Southwark Council and Lambeth Council (depending on the project location) to ensure approvals and compliance run smoothly. We also provide structural drawings and coordination with Building Control inspectors.
How Long Will It Take?
- Design & planning: 4–12 weeks (allow extra time for conservation consultation)
- Technical drawings & approvals: 2–6 weeks
- On-site build:
- Single-storey: 10–14 weeks
- Double-storey: 14–20 weeks
- Add time for bespoke glazing, high-end kitchens, or external landscaping.
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 |
(Premium, conservation-led builds can exceed £150k.)
Why Dulwich Clients Choose Buildaway
- Heritage expertise — familiar with Southwark and Lambeth conservation requirements.
- Transparent pricing — fully itemised quotes, staged payments, no hidden extras.
- 18-month labour warranty — exceeding standard industry cover.
- Fully insured & compliant — Gas Safe, NICEIC, and full liability insurance.
- Design-to-build service — one team managing every stage, ensuring quality and efficiency.
Frequently Asked Questions
Do I need planning permission for my Dulwich extension?
Most likely yes, especially if you’re in a conservation area or planning a double-storey build.
Can I live at home during construction?
Yes, particularly for single-storey projects. Buildaway maintains safe, secure, and tidy work environments.
Will I need to upgrade my boiler or water system?
If adding bathrooms or large kitchen areas, upgrading to a Megaflo or modern boiler is recommended.
What warranty do you provide?
All works come with an 18-month workmanship warranty for total peace of mind.
Next Steps for Dulwich Homeowners
If you’re planning a home extension in Dulwich Village, East Dulwich, or West Dulwich:
- Book a free home consultation to explore ideas and costs.
- Buildaway can manage design, planning, and construction from start to finish.
- Get a transparent, itemised quote and detailed build schedule.
📞 020 8108 0388 📧 info@buildaway.co.uk
Buildaway — trusted by Dulwich homeowners for elegant, compliant extensions that enhance heritage charm and modern living.