Hillingdon · UB3 · UB4 · UB7
House Extensions in Hillingdon
Outer-west borough with semis and bungalows — lofts and side extensions popular. Single and double-storey extensions delivered as a fixed-scope design and build package.
Postcodes covered
Quick answer
Builderr delivers extensions across Hillingdon — UB1, UB3, UB7, UB8, UB10 and HA4. Typical Hillingdon extension cost £42,000–£120,000 over 12–22 weeks. Ruislip, Ickenham, Eastcote and Uxbridge 1930s semis are ideal for double-storey side, rear and wraparound. Larger Home Extension prior approval covers most projects outside CAs.
Hillingdon
House Extensions specialists across Hillingdon.
We deliver house extensions 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.
Every Hillingdon project includes a free desk-based planning assessment before we quote, so you know upfront whether permitted development, prior approval, or full planning applies to your specific address. Our local project manager for Hillingdon has detailed knowledge of the planning department's preferences, the conservation area boundaries, and the common construction details for the prevailing housing stock here.
Quotes for Hillingdon house extensions are fixed-scope after a site survey, valid for 60 days, and never carry provisional sums or open-ended day rates. Every project includes our 10-year structural warranty and 12-month defects period.
Planning in Hillingdon
Local planning rules for house extensions in Hillingdon.
Hillingdon's conservation areas include Ruislip Village, Eastcote Village, Harefield, Ickenham Old Village, Cowley Lock and parts of Northwood. Green Belt and the Colne Valley restrict new development on the western fringe. Outside heritage zones, the borough is planning-friendly with strong PD rights — hip-to-gable lofts, dormers and 6m rear extensions are routinely approved. Two-storey side extensions on the prevailing semi stock are commonly approved with the 1m first-floor setback. The council favours traditional brick and clay tile on extensions matching original stock.
Our planning team handles the full submission for Hillingdon addresses including drawings, Design and Access Statements where required, and pre-application consultation with the council. We tell you whether your house extension is permitted development, prior approval, or full planning before you sign anything.
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 £27,000–£60,750 on a house 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 £135,000.
FAQ
House Extensions in Hillingdon.
How much does a house extension cost in Hillingdon?
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Most house extensions projects in Hillingdon cost £50,000–£220,000 depending on size, spec and structural complexity. Inner London postcodes typically sit toward the upper end; outer borough projects trend mid-range. All Builderr Hillingdon quotes are fixed-price with no provisional sums.
Do I need planning permission for a house extension in Hillingdon?
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Planning rules vary across Hillingdon. We check permitted development eligibility, conservation area status and any Article 4 directions affecting your specific postcode before quoting. Many house extensions fall under permitted development, but conservation areas and listed buildings need full planning.
How long does a house extension take in Hillingdon?
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Typical timeline is 10–20 weeks on site, plus 4–8 weeks for design, structural engineering and approvals. If full planning is required (conservation areas, mansards, larger extensions), add 8–12 weeks for the planning decision before site start.
Do you have house extension references in Hillingdon?
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Yes — we maintain a live reference list for Hillingdon and can connect you with two or three completed clients within the borough. We've delivered projects across nearly every Hillingdon postcode since 2022, so most prospective clients can visit a completed project nearby.
What's included in a Builderr house extension quote in Hillingdon?
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Every Hillingdon quote covers structural design, party wall notices and surveyor coordination, planning or prior approval submission where required, building control, full build, snagging and a 10-year structural warranty. Kitchen units, sanitaryware and bespoke finishes are itemised separately so you can flex spec without losing fixed-price certainty on the build.
Other services in Hillingdon
Get a Hillingdon house extension quote.
Senior consultant call within one business hour. Free desk-based planning assessment for UB3, UB4, UB7 and surrounding postcodes. Fixed-scope price — no provisional sums.
