Cost guide · 2026
HouseExtensionCostEastLondon2026
2026 house extension pricing for East London — Hackney, Tower Hamlets, Newham, Waltham Forest, Redbridge, Barking & Dagenham. Victorian terrace cluster inner, suburban semi stock outer, and the fastest-rising property values in the city.
Quick answer
A house extension in East London costs £50,000–£210,000 in 2026. Side returns £50,000–£88,000; single-storey rears £60,000–£140,000; wraparounds £92,000–£170,000; double-storeys £105,000–£210,000. Hackney and Tower Hamlets Article 4 directions push planning costs up; outer Newham, Redbridge and Barking are more competitive. Cost per m² is £2,750–£4,200.
What moves the price
The seven cost factors that matter most.
Stoke Newington, Dalston, De Beauvoir, Clapton, London Fields, Hackney Central — full planning even for standard PD-sized rears.
Most of E1, E2, E14 — Spitalfields, Wapping, Limehouse heritage stock; full planning standard.
E17 Walthamstow, E10 Leyton, E11 Leytonstone — Victorian terrace dominant; side returns + 3-4m rears typical at £70–110k.
E15 Stratford, E16 Custom House, E20 Olympic Park — premium glazing common, £80–130k for a 4m rear.
Redbridge (Wanstead, Ilford), Barking & Dagenham — 1930s semis with larger gardens, single-storey rears £65–110k with kitchen.
Hackney and Tower Hamlets — CPZ, skip permit, welfare surcharges +£2,000–£3,500 vs outer East.
Dense mid-terrace runs in Walthamstow, Leyton, Hackney trigger PWA on both neighbours — £2,400–£4,800 budget.
Cost breakdown
Where the money actually goes.
Percentage breakdown of a typical mid-spec project. Add or subtract per your finish tier.
| Line item | % of total | £ on avg project |
|---|---|---|
| Groundworks & foundations | 12% | £15,600 |
| Superstructure & roof | 15% | £19,500 |
| Glazing | 13% | £16,900 |
| First fix MEP | 9% | £11,700 |
| Plaster & decoration | 7% | £9,100 |
| Kitchen fit-out | 9% | £11,700 |
| Flooring | 6% | £7,800 |
| Second fix & lighting | 4% | £5,200 |
| External works | 3% | £3,900 |
| Fees | 11% | £14,300 |
| Site management | 6% | £7,800 |
| Margin & contingency | 5% | £6,500 |
Real projects
Worked examples from completed builds.
London zones
Where your borough sits in the price band.
| Zone | Multiplier | Notes |
|---|---|---|
| Inner (E1, E2, E14) | 1.12–1.20× | Tower Hamlets — Article 4, heritage |
| Inner Hackney (E5, E8, N1, N16) | 1.08–1.15× | Hackney — conservation, Article 4 dense |
| Mid (E3, E9, E10, E11, E15, E17) | 1.00–1.08× | Bow, Hackney Wick, Leyton, Stratford, Walthamstow |
| Outer (E4, E6, E7, E12, E13, E16, E20, IG1-IG11, RM8-RM10) | 0.88–0.98× | Newham outer, Redbridge, Barking & Dagenham |
Builderr vs other London builders.
The construction industry has a wide distribution of operators. Here's what changes between a directly-employed, fixed-scope outfit and the alternatives.
| Criterion | Builderr | Typical London builder | Cowboy outfit |
|---|---|---|---|
| Labour model | Directly employed team (PAYE) | Mixed subcontract gangs | Day-rate cash labour |
| Pricing | Fixed-scope itemised quote | Estimate + provisional sums | Verbal price + variations |
| Design & engineering | In-house architect + SE | Outsourced, separate billing | Builder draws on the back of an envelope |
| Planning + LDC handled | Yes — included in price | Often charged extra | Builder asks you to apply |
| Party wall surveyors | Instructed by us | Your responsibility | Skipped (illegal) |
| Building control | Plans + site inspections booked by us | Building Notice route | Not registered |
| Project management | Dedicated PM, weekly photo updates | Foreman doubles up | Owner-manager juggles 5 jobs |
| Payment schedule | Stage payments against signed-off milestones | Weekly invoices | Cash up front |
| Insurance | £10M PL + 10yr structural warranty | £2–5M PL only | No documented cover |
| Snags at handover | <3 typical | 20–30 typical | Walk-off mid-job common |
| Variation creep | 0% — fixed scope | +15–25% over original quote | +40%+ regularly |
Save £26,000–£58,500 on a house extensions.
Industry data (FMB, RICS, Which? Trusted Trader 2024) shows the average London construction project overruns by 18–22% on cost and 25–35% on time. Fixed-scope contracts with a single accountable team eliminate that variance. The savings above assume a typical project at £130,000.
Related
See the full house extensions service page.
FAQ
House Extension Cost East London:
common questions.
How much does a house extension cost in East London?
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An East London house extension costs £50,000–£210,000. Side returns in Walthamstow, Leyton and Hackney terraces £62,000–£88,000. 4m rear extensions with kitchen £85,000–£135,000. Wraparounds £105,000–£165,000. Outer East (Redbridge, Barking & Dagenham) typically 10–15% below inner East pricing.
How do Hackney and Tower Hamlets Article 4 directions affect extension cost?
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They remove permitted development rights, requiring full planning permission even for standard rear extensions that would be PD elsewhere. Across Hackney (Stoke Newington, Dalston, De Beauvoir, Clapton) and most of Tower Hamlets (E1, E2, E14), expect to add £6,500 in planning fees and 10–14 weeks to the project timeline. Pre-application advice is recommended at £600–£1,200.
Which East London borough is cheapest for an extension?
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Barking & Dagenham, outer Redbridge (Goodmayes, Hainault) and outer Newham (Manor Park, East Ham) are the most cost-efficient. Lower trade rates, larger gardens for bigger PD extensions, easier vehicle access, no Article 4 coverage. A 4m rear on a 1930s semi in Barking typically £78,000–£105,000 vs £105,000–£140,000 for the same project in inner Hackney or Tower Hamlets.
What's the most popular extension type in East London?
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Side returns on Victorian terraces in Hackney, Walthamstow, Leyton and Tower Hamlets; single-storey rears on 1930s semis in Redbridge, Barking and outer Newham. The dense terrace stock in Hackney and Waltham Forest means side returns dominate the inner East market; the suburban semis in Redbridge favour wider single-storey rears with open-plan kitchen.
How long does an East London extension take?
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12–22 weeks on site. Side returns 12–14 weeks; 4m rears 15–17 weeks; wraparounds 17–20 weeks; double-storeys 20–22 weeks. Pre-construction is 4–6 weeks for PD projects in outer Redbridge/Barking, 10–14 weeks for full planning in Hackney/Tower Hamlets Article 4 zones.
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