Ground-floor structural opening + twin chimney-breast removal

Brief

1891 Victorian closet-wing terrace in Clapham Old Town CA (SW4), kitchen extension already completed 2019 but cellular ground-floor plan retained as a separate scope. Family wanted the ground floor opened up: 4.8m structural opening between the front reception and existing kitchen-diner (full back-of-front-room spine wall removal), plus both chimney breasts removed at ground-floor level only (upper stack retained on gallows brackets) to free the reception and dining alcoves. No external alteration — Clapham Old Town CA only catches externally-visible work so the whole job runs as internal-only permitted development under building control.

Challenge

1891 lime-mortar spine wall is 225mm solid London stock brick supporting the upper floors and the closet-wing back addition. Single 4.8m span required 305×165 UC44 (not standard 203 series) plus padstones into both party walls — significant propping at 600mm needling centres with timber sole plates and lime-mortar bedjoint preservation. Both chimney stacks (front reception + rear dining) needed ground-floor breast removal with gallows-bracket retention of the upper 3-storey stack — SE design required hanging-beam check for each. Two Party Wall awards (left + right) covered both the spine RSJ landing into party walls + the gallows brackets cantilevering off the party wall masonry. Family in residence throughout — work phased to keep one floor habitable each week.

Solution

Pre-build 7 weeks: structural engineer (Price & Myers) survey + calculation pack £1,650 fixed-fee week 1; Lambeth building control Full Plans submitted week 2, approved week 6 with no comments; 2 Party Wall awards via Berryman week 7. 9-week site: weeks 1–2 propping installation (needling at 600mm centres into both party walls with timber sole plates, acrows to floors above) + careful demolition of 4.8m spine wall section in brick courses retaining adjacent lime-plaster ceiling line; weeks 3–4 305×165 UC44 installed flush with existing ceiling, bearing onto Class B engineering-brick padstones bedded in 3:1 sand-cement on both party walls (Party Wall awards permitted padstone landing); weeks 5–6 twin chimney-breast removal at ground-floor level only — front and rear stacks — with bespoke gallows brackets (1m × 600mm steel triangulated, bolted into party-wall brickwork via M16 chemical anchors on Hilti HIT-HY 200 epoxy, designed by SE for 3-storey upper-stack dead load + wind); weeks 7–8 lime-plaster reinstatement to exposed brick reveals + Crittall W20 3-panel internal screen between snug and kitchen-diner (true Crittall, not aluminium W30) creating the broken-plan zone; week 9 making-good, F&B paint, redecoration of original cornice + ceiling rose (all retained). No external alteration so no planning required.

Outcome

Site completed week 9, on programme. 4.8m structural opening achieved with the RSJ tucked flush above the existing ceiling cornice line — no downstand, no visible beam, single continuous ceiling from front bay to rear closet wing. Both chimney breasts removed at ground floor with gallows brackets cantilevering off party walls — building control sign-off without remediation. Original ground-floor cornice, ceiling rose and dado rail all retained throughout. Crittall W20 3-panel internal screen marks the broken-plan zone (per Wandsworth / Lambeth current trend over fully open-plan) between snug and kitchen-diner without losing sightlines. Resale-equivalent uplift £128k on £38.5k spend = 233% gross ROI — top-decile for a structural-alterations-only scope. First Builderr ground-floor twin gallows-bracket retention (both stacks retained above) — used as portfolio reference for Lambeth + Wandsworth Victorian-terrace open-plan enquiries.