City of London · London
Side Return Extension in City of London
Limited residential stock; primarily apartment fit-outs and listed building work.
City of London
Side Return Extension specialists across City of London.
We deliver side return 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 side return extension fills the narrow alleyway running alongside the rear closet wing on Victorian and Edwardian terraces. By extending out to the boundary wall, the kitchen gains 3–4 metres of additional width and connects to the garden through a glazed rear wall. It's the most common ground-floor extension in London — over 60% of inner-London terraced extensions are side returns — because it unlocks a generous open-plan kitchen-diner without losing garden depth.
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
Side Return Extension cost in City of London 2026.
| Configuration | Cost range | Timeline |
|---|---|---|
| Standard side return (3m wide, full glazed rear) | £55,000–£75,000 | 10–12 wks |
| Side return with steel beams + roof lantern | £70,000–£90,000 | 11–14 wks |
| Side return + kitchen install | £85,000–£110,000 | 12–15 wks |
| Premium side return (Crittall, structural glass) | £100,000–£120,000 | 13–16 wks |
Local advantage
Eight years of side return 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
Side Return 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 £17,500–£39,375 on a side return 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 £87,500.
FAQ
Side Return Extension in City of London.
How much does a side return extension cost in City of London?+
Side Return Extension projects in City of London typically cost £55,000–£120,000. City of London sits across postcodes EC1, EC2, EC3, EC4; local rates align with the wider London market.
Do side return 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 side return extension projects across all City of London postcodes including EC1, EC2, EC3, EC4.
How much does a side return extension cost in London?+
Typically £55,000–£120,000 depending on size, glazing spec and kitchen inclusion. A 3m × 4m side return without kitchen runs around £60–80k; with premium kitchen and Crittall glazing closer to £110k+.
Do I need planning permission for a side return?+
Most fall under permitted development. Conservation areas and Article 4 zones usually need full planning. We screen this on every quote.
Get a City of London side return 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.
Side Return Extension across London