Thinking about extending your home in the Isle of Dogs or the surrounding E14 postcode? Whether you’re planning a sleek riverside kitchen-diner near Millwall Dock, adding bedrooms with a double-storey rear extension in Cubitt Town, or creating a bright side return in a Victorian terrace near Mudchute, understanding realistic 2025 costs will help you plan confidently.
This guide is written for Isle of Dogs homeowners — covering Canary Wharf, South Quay, Cubitt Town, and Millwall — who want clear pricing, practical planning advice, and trusted local insight. It’s based on current East London market averages and the hands-on experience of Buildaway, a reputable construction company known for transparent quotes and an 18-month labour warranty.
How Much Does a House Extension Cost in Isle of Dogs (2025)?
Isle of Dogs properties sit in the mid-to-upper East London price bracket — higher than outer boroughs, but still offering competitive value for central riverside living. Here’s what you can expect:
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
Typically match single-storey rates: £2,200 – £2,900 per m² depending on structure and glazing. These are fair mid-market Isle of Dogs rates for insured builders delivering high-standard finishes and reliable aftercare.
What Drives the Price Up or Down
- Size & footprint – larger extensions require more foundation, roofing, and materials.
- Structural steel (RSJs) – removing load-bearing walls adds £2k–£6k+.
- Foundations & drainage – older dockside sites or shared drainage can increase costs.
- Roof & glazing design – flat roofs with skylights are cheaper; roof lanterns or bifold doors add £3k–£8k+.
- Kitchens & bathrooms – kitchens £10k–£25k+, bathrooms £6k–£15k+.Isle of Dogs
- Heating & plumbing – adding bathrooms may require a Megaflo/unvented system (£2.5k–£4.5k).
- Finishes & carpentry – flooring, bespoke storage, and decorating impact the total.
- Access & parking – narrow streets or riverside walkways can slightly increase labour logistics.
Planning Permission & Building Control in Isle of Dogs
- Many single-storey rear or side extensions fall under Permitted Development (PD) if within size limits.
- Full planning is required for double-storey, front, or large wrap-around extensions.
- Conservation areas near Millwall Dock and parts of Cubitt Town remove PD rights.
- Building Control approval is mandatory for structural work, insulation, drainage, and electrics.
A qualified contractor or architect can guide you through 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 extra time for bespoke kitchens, glazing, or 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 |
(Larger or high-end finishes may exceed £150k.)
Why Isle of Dogs Clients Choose Buildaway
- Local expertise — familiar with riverside properties, dockside terraces, and modern apartment conversions.
- Transparent quoting — detailed staged payments, no hidden costs.
- 18-month labour warranty — longer than average in East London.
- Fully insured & compliant — Gas Safe, NICEIC, public and employer liability certificates included.
- Reliable project management — we handle trades, timelines, and Building Control liaison.
Frequently Asked Questions
Do I need planning permission for my Isle of Dogs extension?
Smaller single-storey rears may not need it, but double-storey or front extensions and properties in conservation areas usually do.
Can I live at home during construction?
Yes, especially for single-storey projects. Temporary kitchens may help reduce disruption.
Will I need a new boiler or hot water system?
Adding bathrooms or large kitchens often requires upgrading to a Megaflo/unvented cylinder.
What guarantee do you offer?
Buildaway provides an 18-month labour warranty on all structural and fit-out work for peace of mind.
Next Steps for Isle of Dogs Homeowners
If you’re ready to explore your extension:
- Book a free home visit to assess feasibility and budget.
- We can provide design & planning support if you don’t yet have drawings.
- Receive a transparent, itemised quote so you know where every pound goes.
📞 020 8108 0388 📧 info@buildaway.co.uk
Buildaway — trusted by Isle of Dogs homeowners for stylish extensions, kitchen renovations, and full home transformations.