Highbury Victorian terrace — master ensuite carve-out + family bathroom paired retrofit

Brief

1885 Victorian end-of-terrace in Highbury Fields, N5, within the Highbury Fields Conservation Area but not listed. Owner-occupier family of four. Two bathrooms in dated late-1990s condition: a single family bathroom 5.8m² on the half-landing and no master ensuite. Brief: carve a new 4m² master ensuite off the rear of the master bedroom (taking the back third of the bedroom which had originally been a Victorian closet-wing alcove) and rebuild the family bathroom to spec matching the recently restored ground-floor period scheme — Burlington traditional brassware, encaustic-cement floor tiles, roll-top cast-iron bath, bespoke oak vanity. Paired commission delivered as a single 8-week site visit.

Challenge

Four issues. (1) Master ensuite carve-out — taking the rear third of the master bedroom required a new non-loadbearing stud partition + new doorway + extending soil-pipe routing internally up from the existing family bathroom soil stack on the floor below (Victorian terrace stacks ran externally on the rear elevation in this terrace, hidden in the closet-wing void) — Building Control Part H approval for the new branch + new internal stack vent through the roof. (2) Joists — original Victorian joists 75×175 across 4.2m span were undersized for the cast-iron Burlington Buckingham bath weight + occupant + decoupled marble floor; sister joists C24 47×195 specified for the family bathroom zone (the master ensuite shower-only design avoided this issue). (3) Encaustic tile longevity — Bert & May Verena pattern encaustic-cement tiles are pigmented through the body but porous; specification required Lithofin 4-coat sealer (impregnator + colour intensifier + matt-finish + maintenance seal) for 25-year wet-area durability. (4) Heritage detailing — the family bathroom needed to read as a period restoration despite being a fresh rebuild; original cornice profile measured + replicated by Pavilion Plaster; original architrave and skirting profile measured + replicated; new sash window replacement on the rear elevation matched original 1885 sightline.

Solution

Pre-app not required (within CA but works internal + rear sash replacement matches original). Building Notice route Islington Building Control. Build 8 weeks. Week 1 strip-out both bathrooms + protection of retained features + structural survey confirmation. Weeks 2–3 structural + soil-pipe routing. C24 47×195mm sister joists bolted to existing Victorian 75×175mm joists in family bathroom zone + steel hangers + Rockwool Flexi 100mm acoustic. New non-loadbearing stud partition between master bedroom + new ensuite — 70mm metal stud + 2× 15mm acoustic plasterboard + Rockwool RWA45 25kg/m³ + Genie clip-on resilient bar system to achieve Rw 50dB acoustic separation. New internal soil-pipe routing from family bathroom up through closet-wing void to new master ensuite WC + basin + new stack vent through roof Part H compliant. Weeks 3–4 first fix plumbing + electrics. Wet-area waterproofing both bathrooms — Schlüter-KERDI membrane over 18mm marine ply overlay bedded in epoxy + KERDI-DRAIN linear drain to master ensuite walk-in shower. Weeks 5–6 finishes. Family bathroom Bert & May Verena pattern encaustic-cement floor tiles 200×200mm + Lithofin 4-coat sealer + handmade glazed metro tiles to walls in soft cream + Edward Bulmer Brimstone paint above tile line + replicated cornice by Pavilion Plaster. Burlington Buckingham 1700mm roll-top cast-iron bath + Burlington traditional pillar taps + Burlington high-level WC + bespoke single-basin oak vanity 0.9m with Carrara marble worktop + Burlington traditional taps + reeded mirror cabinet above. Master ensuite Carrara marble 600×600mm tile to floor + walls + walk-in shower 1.2m × 0.9m + 8mm low-iron glass screen + Burlington traditional thermostatic shower set + bespoke single-basin oak vanity 0.85m. Weeks 7–8 electric UFH thermostatically controlled both bathrooms + Drummonds brass heated towel rails + John Cullen brass wall sconces + Selectaglaze secondary glazing on family bathroom rear sash window for acoustic + thermal. Replacement timber sash window on rear elevation (Mumford & Wood double-glazed, slim sightline matching original 1885 profile) U-value 1.4 W/m²K. Week 8 commissioning + Building Control final + snagging + handover.

Outcome

Building Control final certificate issued week 8. Project completed Q2 2026, on programme. Master suite uplifted from no-ensuite to functional 4m² ensuite + 5.8m² family bathroom rebuilt to period-luxury spec matching the recently restored ground floor. Resale agent (Hamptons Islington) valued the combined uplift at £135,000 against £82,500 spend = 164% gross ROI. The conversion of a former closet wing into ensuite + maintained reasonable master bedroom size (12.5m² remaining after carve-out vs original 16.5m²) was cited as a model for the typology by Islington Society N5 case study Q3 2026. Builderr first paired master-ensuite-carve-out + family-bathroom commission delivered as a single 8-week site visit + first encaustic-cement tile install with Lithofin 4-coat sealer specification + first Genie clip-on resilient bar acoustic separation Rw 50dB between bedroom + ensuite. Islington 3rd portfolio case study + Highbury Fields first.