City of London · London
Rear Extension in City of London
Limited residential stock; primarily apartment fit-outs and listed building work.
City of London
Rear Extension specialists across City of London.
We deliver rear extension projects across the full City of London postcode set — EC1, EC2, EC3, EC4. Limited residential stock; primarily apartment fit-outs and listed building work.
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 City of London 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 City of London 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 City of London.
Familiarity with City of London's planning officers, party wall surveyors and approved inspectors cuts weeks off the approval timeline. We deliver consistent quality across all 4 postcodes the borough covers.
Recent City of London 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 City of London.
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 City of London.
How much does a rear extension cost in City of London?+
Rear Extension projects in City of London typically cost £50,000–£130,000. City of London sits across postcodes EC1, EC2, EC3, EC4; local rates align with the wider London market.
Do rear extensions in City of London need planning permission?+
Limited residential stock; primarily apartment fit-outs and listed building work. 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 City of London postcodes?+
Yes — we deliver rear extension projects across all City of London postcodes including EC1, EC2, EC3, EC4.
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 City of London rear extension quote.
Senior consultant call within one business hour. Fixed-scope quote for your City of London project — no provisional sums.
Other types in City of London
Explore other build types in City of London.
Rear Extension across London