1930s semi rear extension + loft + energy retrofit, W5

Brief

A 1934 mock-Tudor semi on Pitshanger Lane W5, mid-tier Ealing residential market. Clients: a software architect and gallery curator with two young children planning a 15-year hold; brief was a comprehensive 'forever home' renovation transforming a tired 3-bed (90m² original) into a 5-bed family home (148m² post-renovation) with deep-retrofit thermal upgrade and open-plan family living. Budget £285k including ASHP, MVHR, full rewire, replumb, kitchen, two bathrooms and external works. Phased works programme — family vacated to rental for 26 weeks. Pitshanger Lane within character area but not formally conservation area; permitted development applied with prior approval for the 6m larger home extension neighbour consultation.

Challenge

Three connected challenges. (1) The 1934 mock-Tudor envelope (cavity wall, brick + tile-hung first floor, half-timbered gables, double-bayed front) had to be retained completely on the front and side elevations — Ealing planning officer pre-application advice was clear that visible elevations must preserve mock-Tudor character even though property is not formally listed or in a conservation area; rear elevation could be modernised. (2) Deep-retrofit thermal upgrade (cavity wall insulation, internal wall insulation to solid party wall, loft 400mm, suspended floor insulation 150mm, MVHR ducting, ASHP integration with retained-and-upsized radiator network) required floors up, ceilings down, and full service replacement — sequencing critical to maintain 26-week programme. (3) Hip-to-gable loft conversion required rebuilding the original mock-Tudor hip-end gable in matching salvaged tile-hanging and authentic half-timbered cladding — sourcing reclaimed materials and matched-profile timber added 3 weeks of lead time but was non-negotiable for visual consistency.

Solution

Pre-construction phase (10 weeks): MCS heat loss survey, ASHP design at 9kW Vaillant aroTHERM plus R290 with weather compensation; emitter audit (8 existing radiators retained, 6 upsized Type 22 → Type 33, 3 new for new loft and extension); MVHR design Zehnder ComfoAir Q350 with PE100 semi-rigid ducting routed in service voids; Pitshanger Lane neighbour consultation for 4.5m single-storey rear (8 weeks Prior Approval) and certificate of lawfulness for hip-to-gable loft (8 weeks). Build programme weeks 1–26. Weeks 1–4: strip-out, floors up, asbestos abatement (Artex ceilings throughout — Type 2 survey identified £2,800 abatement); structural steel for rear opening 6.2m × 3.0m + new loft trimmer; Pitshanger party wall notices to one neighbour (semi-detached). Weeks 5–10: rear extension construction (single-storey, traditional masonry to match existing brick, EPDM flat roof with two integrated rooflights, aluminium bifold doors); foundations on existing strip foundation extended; building control inspections at each stage. Weeks 11–16: hip-to-gable loft construction (steel beams, rebuild gable in salvaged tile-hanging from Tilbury Reclaim, half-timber cladding in seasoned oak with linseed-oil finish matched to existing), rear dormer, new staircase to loft from first-floor landing. Weeks 17–22: M&E first-fix — full rewire (CU+RCD), full replumb, ASHP install + 250L heat-pump-compatible cylinder + MVHR install + UFH wet to ground floor (75mm screed); CWI to cavity walls; internal wall insulation 60mm PIR to two party walls; loft insulation 400mm; suspended floor insulation 150mm. Weeks 23–26: second-fix, kitchen install (Howdens Burford Cashmere with Caesarstone Statuario worktop and 1.8m island), bathrooms × 2 (Villeroy & Boch + Crosswater), decoration, snagging. Ealing planning prior approval granted at week 8; building control completion certificate week 27. EPC E (54) → B (84).

Outcome

Comprehensive 'forever home' delivered on programme and budget (£287,500 final, 0.9% over £285,000 budget on additional asbestos abatement). 5-bedroom family home with master suite in loft, open-plan family kitchen-diner-living on ground floor, original front elevation mock-Tudor character retained intact. EPC improvement E (54) → B (84) — 30-point improvement; annual heating bill £2,800 (gas combi pre-renovation) → £980 (ASHP at SCOP 3.8); £1,820 annual saving; BUS grant £7,500 contributed; net ASHP install £4,200. Floor area 90m² → 148m² (+64%). Property valuation: pre-renovation £880,000; post-renovation £1,265,000 (£385,000 uplift on £287,500 build cost — 134% gross ROI). Pitshanger Lane neighbour consultation completed without objection; planning officer praised retention of mock-Tudor character. Pitshanger first case study for Builderr portfolio.