Hillingdon · London
Side Return Extension in Hillingdon
Outer-west borough with semis and bungalows — lofts and side extensions popular.
Hillingdon
Side Return Extension specialists across Hillingdon.
We deliver side return extension projects across the full Hillingdon postcode set — UB3, UB4, UB7, UB8, UB9, UB10, HA4, HA6. Outer-west borough with semis and bungalows — lofts and side extensions popular.
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 Hillingdon 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 Hillingdon 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 Hillingdon.
Familiarity with Hillingdon's planning officers, party wall surveyors and approved inspectors cuts weeks off the approval timeline. We deliver consistent quality across all 8 postcodes the borough covers.
Recent Hillingdon 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 Hillingdon.
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 Hillingdon.
How much does a side return extension cost in Hillingdon?+
Side Return Extension projects in Hillingdon typically cost £55,000–£120,000. Hillingdon sits across postcodes UB3, UB4, UB7, UB8; local rates align with the wider London market.
Do side return extensions in Hillingdon need planning permission?+
Outer-west borough with semis and bungalows — lofts and side extensions popular. 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 Hillingdon postcodes?+
Yes — we deliver side return extension projects across all Hillingdon postcodes including UB3, UB4, UB7, UB8, UB9, UB10, HA4, HA6.
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 Hillingdon side return extension quote.
Senior consultant call within one business hour. Fixed-scope quote for your Hillingdon project — no provisional sums.
Other types in Hillingdon
Explore other build types in Hillingdon.
Side Return Extension across London