W11 stucco terrace full-house basement with lap pool, cinema and wine cellar

Brief

1854 5-storey stucco terrace in Notting Hill (W11), RBKC's Phillimore/Linden Gardens fringe — owners are private-equity principal + barrister, 12-year residents who'd outgrown the 5-bed 3-reception house's lateral footprint. Brief: single-storey new basement to maximum RBKC SPD allowance — 9.8m × 2.4m lap pool with Endless Pools current generator, 12-seat THX-Reference Atmos home cinema, climate-zoned wine cellar for the husband's 1,850-bottle Burgundy + Bordeaux collection, gym, plant room, staff WC. No double or triple basement (RBKC SPD hard limit). No front lightwell (Linden Gardens stucco frontage refusal universal). Rear garden footprint capped at 50% with minimum 30% soft landscaping retained above. Construction working hours 7am–6pm Mon–Fri + 8am–1pm Sat strictly enforced. Family decanting to Bayswater rental for full 38-week site duration.

Challenge

RBKC Basements SPD (2021) is the most restrictive basement policy in London. Hard caps: one storey only (regardless of how many neighbours had pre-2014 double basements on the street); 50% rear garden footprint maximum; 30% soft landscaping above basement minimum; front lightwells refused on Linden Gardens stucco frontage; CTMP + CMP + 7am–6pm working hours strictly enforced with RBKC environmental health monitoring; arboricultural impact assessment for the 4 mature plane trees in the front and rear gardens (all within 12m of works). Mandatory pre-application engagement with RBKC conservation + planning + drainage + arboricultural officers — 3 pre-app meetings at £1,250 + VAT each. Mandatory Basement Impact Assessment by chartered geotechnical engineer (Card Geotechnics) covering ground stability, hydrogeology, structural impact on 5 adjacent properties (mid-terrace + flank-wall), surface-water drainage. London Clay underpinning to 2.95m head height (clients wanted pool ceiling at 2.7m clear) required sequential bay-by-bay underpinning in 1m bays with reinforced concrete pin foundations to 4.2m total depth. 6 Party Wall awards via Peter Barry (3 immediate neighbours left, 3 immediate neighbours right — surveyor fees £62,500 total). 9.8m × 2.4m pool tank required mass-concrete tanked construction (1,800mm thick base slab, 350mm walls) with Sika Sarnafil Type A tanking membrane + Newton CDM Type C cavity drain combined (Type A+C). Pool plant room ventilation routed through 18m of insulated ductwork to rear roof terrace — RBKC condenser-noise condition 35 dB(A) at boundary measured. Cinema acoustic spec required room-within-room construction with 4-leaf 70mm Genie clip wall on resilient bars + 250mm acoustic floating floor on Sylomer SR42 isolation pads — IIC 72 / STC 68 measured. Wine cellar dual-zone climate (8°C reds / 12°C whites + 14°C drinks fridge) required Wine Guardian D050 split compressor + heritage-grade vapour barrier + boric-acid-treated softwood racking from Bordeaux specialist La Cave Saint-Germain.

Solution

Pre-build 22 weeks: pre-app meeting 1 week 1 (£1,250 + VAT) covered SPD compliance baseline, BIA scope, arboricultural constraint; Card Geotechnics BIA week 2–9 (£14,800 — ground investigation, hydrogeology, structural impact, party-wall impact, SUDS strategy); pre-app meeting 2 week 11 (£1,250) for design review with RBKC conservation + drainage officers; pre-app meeting 3 week 14 (£1,250) finalising arboricultural strategy with RBKC tree officer — 4 mature planes protected with no-dig root protection zone + protective fencing per BS 5837; full planning + LBC combined application submitted week 15 with BIA + CTMP + CMP + arboricultural impact assessment + heritage statement + design + access statement (44-document submission pack); RBKC validation week 16; consultation weeks 17–20 (5 immediate neighbour objections received, RBKC tree officer site visit, drainage officer SUDS sign-off); RBKC planning committee determined week 22 — APPROVED with 11 conditions including BIA + CTMP + CMP + arboricultural monitoring + Party Wall agreements + Sika Type A+C waterproofing specification + 7am–6pm working hours + pool plant noise 35 dB(A) at boundary + soft-landscape reinstatement to 30%+ + condition discharge schedule. 6 Party Wall awards via Peter Barry served weeks 16–18, all 6 awards in hand by week 22 (£62,500 total surveyor fees including 3 neighbour surveyor appointments at neighbours' choice). 38-week site: weeks 1–4 site protection + arboricultural fencing + RPZ + tree-protection-officer sign-off + decant client to Bayswater rental; weeks 5–16 sequential bay-by-bay underpinning in 1m bays with reinforced-concrete pin foundations to 4.2m depth — 56 pins total — each pin excavated, formed, poured, propped, cured (3-day cycle per pin) before adjacent bay started — Card Geotechnics ground-movement monitoring at every bay; weeks 17–22 mass-concrete pool tank construction — 1,800mm thick base slab + 350mm walls + Sika Sarnafil Type A tanking membrane + Newton CDM Type C cavity drain combined; weeks 23–26 cinema room-within-room construction — 4-leaf 70mm Genie clip wall on resilient bars + 250mm acoustic floating floor on Sylomer SR42 isolation pads + Atmos ceiling speaker positions cast into floor zone; weeks 27–30 wine cellar dual-zone climate fit — Wine Guardian D050 compressor + heritage vapour barrier + La Cave Saint-Germain boric-acid-treated softwood racking; weeks 31–34 plant room + gym + staff WC fit-out + 18m insulated pool plant ductwork to rear roof terrace + pool plant acoustic enclosure (40 dB attenuation); weeks 35–37 finishes — Crema Marfil pool mosaic + Atmos cinema audio commissioning + wine cellar climate commissioning + gym mirror walls + lighting commissioning by John Cullen; week 38 RBKC tree officer sign-off + landscape reinstatement (40% soft landscaping above basement — exceeds 30% SPD minimum) + Card Geotechnics post-construction ground-movement final report + Party Wall surveyor closing inspections + RBKC drainage officer SUDS sign-off + condition discharge submitted + practical completion + handover.

Outcome

Site completed week 38, on programme. RBKC SPD single-storey limit + 50% garden footprint cap + 30% soft-landscape minimum all complied with first-time and signed off by RBKC tree officer at handover (40% soft landscape delivered — 10 percentage points above minimum). 9.8m × 2.4m lap pool with Endless Pools current generator at 2.7m ceiling clear delivered with Sika Type A+C waterproofing certificate + 10-year guarantee from British Structural Waterproofing Association member. 12-seat THX-Reference 7.2.4 Atmos cinema independently measured at IIC 72 / STC 68 acoustic isolation (target was IIC 65 / STC 60). 1,850-bottle dual-zone climate-controlled wine cellar holding 8°C reds + 12°C whites + 14°C drinks fridge — La Cave Saint-Germain commissioning sign-off. Pool plant room noise measured at 33 dB(A) at boundary against RBKC condition 35 dB(A). 4 mature plane trees protected throughout — no canopy or root damage, RBKC tree officer commended the no-dig RPZ methodology in handover inspection report. All 11 planning conditions discharged within 6 weeks of practical completion. Total all-in cost £1.45M build (excluding c.£185k design/consents/SE/BIA/PW/CIL — total project £1.635M). Resale-equivalent uplift £2.8M (basement adds c.£2.8M in W11 SPD-cap territory — comparable W11 lap-pool/cinema basements sell for c.£280k–£320k uplift per amenity in £20M+ Notting Hill comps) = 71% gross ROI on construction cost. House withdrawn from sale and retained as principal residence; clients' instruction extended Builderr to a Surrey country-house renovation. Builderr first lap-pool basement + first 1,850-bottle climate-zone wine cellar + first IIC 72 acoustic-isolated cinema + first 6-neighbour Party Wall surveyor schedule + first Card Geotechnics BIA at this scope + first 56-pin sequential bay-by-bay underpinning to 4.2m. RBKC SPD-compliance pattern now serves as Builderr's reference Mayfair/Kensington/Holland Park enquiry pack.