Chislehurst 1930s detached double-storey rear + loft
Bromley · 1934 detached · BR7 · large rear garden, no CA
Brief
Four-bedroom 1930s detached in Chislehurst — DSE + L-shape loft for 5-bed family home with garden room and master suite.
Challenge
Generous 22m rear garden allowed 6m DSE but BR7 planning officers scrutinise design — needs sympathetic to 1930s detached character. Loft conversion with L-shape dormer required complex steel layout over existing kitchen. Family wanted no out-of-house move during build.
Solution
Planning route (not PD — DSE over 4m needs planning) with brick-match Tudor-style detailing on rear elevation, slate-look tile roof to match original. 6m × 4.5m double-storey rear: ground floor garden room with 5m sliding glass + roof lantern; first floor master bedroom + en-suite. L-shape dormer over existing kitchen with structural steel frame. Phased sequence — DSE shell weatherproofed first allowing kitchen to remain functional, then internal connection. Family stayed in occupation throughout.
Outcome
Planning approved at first submission. 5-bedroom layout with master suite (en-suite + walk-in), garden room (now favourite family room), upgraded kitchen with new island. Sale comp value uplift estimated £180,000–£240,000 on £215,000 spend. BR7 catchment school access drove decision to extend rather than move.
Spec
Project specification.
Gallery
Inside the build.
"We chose to stay rather than move out — Builderr's phased approach (shell first, then internal connection) made it possible. The garden room is now the most-used room in the house and the master suite means we don't have to share a bathroom with two teenagers anymore."
— Mark and Sarah Hennessy, Chislehurst BR7
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 £43,000–£96,750 on a house extension.
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 £215,000.
Want a build like Bromley?
Get a fixed-scope quote with the same direct-labour delivery. Senior consultant call within one business hour.
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