Victorian terrace converted to two self-contained flats, E16

Brief

1898 Victorian end-of-terrace E16 Canning Town — 142m² over three storeys + cellar — vacant former HMO purchased as buy-to-let investment. Client (London-based property investor + structural engineer) brief: convert into two self-contained flats — ground floor 2-bed (62m² incl. cellar storage) and upper 2-bed (74m² over first + second floors with new mansard) — meet Building Regs Part E (acoustic), Part F (ventilation), Part B (fire), Part M (accessibility — Cat 2 ground floor), Part L (energy — target EPC C both flats). Each flat fully self-contained: own entrance, kitchen, bathroom, boiler, mains intake, smart meter. Budget £218,000 (£1,535/m² blended). Newham planning — flat conversion lawful via Class G permitted development (subject to prior approval) for the upper unit + Class A for the rear-extension at ground.

Challenge

Five compounding constraints. (1) Part E acoustic — converting single dwelling to two flats triggers Part E in full: minimum 45dB DnT,w airborne party-wall/floor + 62dB L'nT,w maximum impact noise. Existing Victorian timber-joist floor performs ~78dB impact untreated — major intervention required. (2) Part B fire — two-flat conversion requires 30-minute fire resistance between flats: upgraded floor, fire doors FD30s to both entrance lobbies, mains-wired interlinked smoke alarms each flat, escape windows to bedrooms. (3) Separate services — each flat needs independent gas + electric + water + drainage + boiler — services routed without compromising fire compartmentation. (4) Sound test mandatory at completion: pre-completion sound test by certified acoustic consultant required by building control before signing off — failure = re-work + delay. (5) Newham prior approval (Class G PD for upper flat) — 8-week determination — proposal must demonstrate adequate light, outlook, internal space (London Plan minimum space standards: 2-bed/4-person flat 70m² minimum — design achieved 74m² upper, 62m² lower).

Solution

Pre-design + consents 11 weeks: Class G prior approval secured (zero amendments, 7 weeks), Class A rear extension at ground for kitchen-diner full planning (10 weeks), Part E acoustic strategy report by acoustic consultant (Sustainable Acoustics) at RIBA Stage 4, fire strategy by approved inspector (Hilson Moran). Build 26 weeks. Weeks 1–4: Strip out + structural — soft-strip throughout retaining usable salvage (chimney pieces, internal doors). Joist condition survey — 12 of 38 joists sistered for span/spring; cellar slab insulated to 0.18 U-value. Steel frame for ground-floor rear extension (RSJ + posts) cast week 4. Weeks 5–10: Acoustic floor + party-wall upgrade. Floor between flats: existing 230mm joist + new 25mm Hush HD1014 acoustic mat + 25mm Regupol Sonus batten + 18mm WBP ply + engineered oak finish; underneath, independent isolated ceiling (Resilient Bar hangers + 100mm Rockwool RWA45 quilt + 2×15mm Knauf Soundshield acoustic plasterboard) — total floor build-up 198mm. Party wall (shared with adjoining terrace): independent 50mm metal stud 50mm clear + 50mm Rockwool + 2×15mm Soundshield. Weeks 11–16: First-fix services. Twin Bosch Greenstar 30kW combis (one per flat), independent gas + electric routes through dedicated fire-stopped service voids, MID-certified smart meters (Energy Performance Certification Operator approved), separate stopcocks, copper sub-mains. Mechanical extract per flat: Vent-Axia Lo-Carbon dMEV kitchen + bathroom continuous extract (Part F) + 15-minute over-run. Fire-rated penetrations (Hilti CP 670 cable transit, intumescent collars at pipework). Weeks 17–22: Second-fix + finishes. Ground floor: 28m² rear extension over original kitchen + reception (steel-frame structural opening to garden); Howdens Hockley shaker kitchen (£8,500); Vitra bathroom; engineered oak floor. Upper flat: rear dormer loft conversion (40m³ Class B PD compliant) + Velux to front; bedrooms over first floor; kitchen-diner at first-floor rear; bathroom + WC mid-floor. Weeks 23–26: Acoustic + EPC sound test + commissioning. Pre-completion sound test by Sustainable Acoustics: airborne DnT,w measured 52dB (Part E target 45dB — exceeds); impact L'nT,w measured 58dB (Part E target 62dB max — exceeds). EPC both flats — ground D (66), upper C (73) — target C achieved upper, D acceptable ground. Building control completion both flats week 26.

Outcome

Two self-contained 2-bed flats from one Victorian terrace. Part E sound test exceeded target by 7dB airborne and 4dB impact. Part B fire compartmentation certified. Fire doors FD30s + interlinked smoke alarms across both flats. London Plan minimum space standards exceeded — ground 62m² (target 61m² 2-bed/3-person), upper 74m² (target 70m² 2-bed/4-person). Property valuation: pre-renovation £495,000 (single 3-bed in poor condition); post-renovation £760,000 combined (ground £335,000 + upper £425,000) — £265,000 uplift on £218,000 spend (122% gross ROI). Rental yield 6.4% gross combined (£1,650 + £2,200/month). Builderr first Newham case study; first flat conversion at this acoustic spec. Newham building control praised Part E approach as best practice for borough — featured in officer training material 2026. Two long-let tenancies secured at completion via Foxtons + Dexters; both tenants in occupation within 3 weeks of practical completion.