Islington · London
Rear Extension in Islington
Dense Georgian and Victorian stock with heavy conservation — full planning typical.
Islington
Rear Extension specialists across Islington.
We deliver rear extension projects across the full Islington postcode set — N1, N5, N7, N19, EC1. Dense Georgian and Victorian stock with heavy conservation — full planning typical.
A rear extension projects from the back of the house into the garden, creating open-plan living, a new kitchen or a family room. Single-storey rears can extend up to 6 metres on detached homes and 8m by prior approval under the Larger Home Extension scheme. They suit terraces, semis and detached houses across London and remain the most popular extension type by volume.
Every Islington project includes a free desk-based planning assessment before we quote. We know the local planning officers, party wall surveyors and approved inspectors by name.
Costs
Rear Extension cost in Islington 2026.
| Configuration | Cost range | Timeline |
|---|---|---|
| Single-storey rear (3m deep) | £50,000–£75,000 | 10–12 wks |
| Single-storey rear (5–6m deep) | £70,000–£100,000 | 12–14 wks |
| Rear + kitchen install | £85,000–£120,000 | 13–16 wks |
| Premium rear (structural glass, Crittall) | £105,000–£130,000 | 14–18 wks |
Local advantage
Eight years of rear extension work in Islington.
Familiarity with Islington's planning officers, party wall surveyors and approved inspectors cuts weeks off the approval timeline. We deliver consistent quality across all 5 postcodes the borough covers.
Recent Islington work
Rear Extension examples.
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 £18,000–£40,500 on a rear extension in Islington.
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 £90,000.
FAQ
Rear Extension in Islington.
How much does a rear extension cost in Islington?+
Rear Extension projects in Islington typically cost £50,000–£130,000. Islington sits across postcodes N1, N5, N7, N19; local rates align with the wider London market.
Do rear extensions in Islington need planning permission?+
Dense Georgian and Victorian stock with heavy conservation — full planning typical. We carry out a free desk-based planning assessment for your specific address before quoting, identifying whether permitted development, prior approval, or full planning applies.
Do you work across all Islington postcodes?+
Yes — we deliver rear extension projects across all Islington postcodes including N1, N5, N7, N19, EC1.
How much does a rear extension cost in London?+
Typically £50,000–£130,000 depending on depth, glazing spec, kitchen inclusion and any structural complications.
Do I need planning permission?+
3m deep and under is permitted development. 3m–6m on a terrace or semi requires prior approval under the Larger Home Extension scheme. Beyond that or in conservation areas, full planning.
Get a Islington rear extension quote.
Senior consultant call within one business hour. Fixed-scope quote for your Islington project — no provisional sums.
Other types in Islington
Explore other build types in Islington.
Rear Extension across London