Double-storey rear extension, Seven Kings

Brief

A 1952 post-war semi-detached in Seven Kings, Redbridge — IG3, no conservation area, original PD rights intact. The property: 82m², three bedrooms, one bathroom, a compact 12m² kitchen at the rear with a window looking onto a generous 14m-deep garden. The clients — a professional couple with a toddler — needed a fourth bedroom, a family-scale kitchen, and a utility room, all without disrupting the three existing bedrooms on the first floor.

Challenge

The rear garden depth (14m) gave room for a deep extension, but the client's preferred depth of 5.5m triggered the need for a full planning application under the Prior Approval route (the Larger Home Extension Scheme allows up to 6m for semi-detached under Prior Approval, but Redbridge Planning required full planning for the proposed depth given the site geometry and relationship with the rear boundary). The planning officer's initial feedback was that the extension was 'overbearing' relative to the rear neighbours — the rear boundary was only 8.5m from the proposed new rear wall of the extension. Architect revised the scheme: the first-floor addition was set back 1.5m from the full-depth ground floor (creating a first-floor footprint of 4m × 4m over a ground floor footprint of 5.5m × 4m) — this stepped massing reduced the visual impact to rear neighbours and satisfied the planning officer's concerns. Party Wall: Section 6 notice served to left and right neighbours (foundation excavation within 3m of their foundations); both used the Agreed Surveyor route; Awards sealed in 5 weeks.

Solution

Revised massing: ground floor 5.5m × 4m (22m²) with full-width sliding glass wall to garden; first floor 4m × 4m (16m²) with Juliet balcony to rear — the stepped massing creates a roof terrace on the ground-floor flat roof (covered with EPDM and a decking platform, accessed via the Juliet balcony doors). Full planning permission: granted at 9 weeks with no amendments after the massing revision. Structural: the first-floor addition bears on the extended ground-floor masonry — a 178mm × 102mm channel section steel ties the first-floor addition back to the existing first floor of the host property. Foundation: 450mm wide strip footings at 0.9m depth on London Clay. Ground floor: kitchen-diner (24m² — 5.5m × 4m, open to existing dining room via new 2.4m steel-lintel opening); sliding glass wall (3.6m × 2.1m, aluminium, anthracite grey, Schüco ASS 70 FD) to south-facing garden. First floor: new bedroom (15m²) with Juliet balcony; en-suite shower room (4m²); both accessed off new landing extension. Roof terrace: 22m² of first-floor flat roof converted to accessible terrace (EPDM waterproofing, composite decking, 1.1m-high glass balustrade — balustrade requires planning permission, included in the main planning application). EV charger: 7kW Hypervolt installed to existing garage (separate garage to rear, accessed via side passage); SWA cable run 18m under the garden from the consumer unit.

Outcome

Floor area added: 38m² (22m² ground floor kitchen-diner + 16m² first-floor bedroom and en-suite). Property: 82m² to 120m² — a 46% increase. Bedroom count: 3 to 4. Roof terrace: 22m² accessible — rare for a post-war semi in this part of Redbridge; the terrace is directly accessible from the master bedroom via the Juliet balcony. EPC: unchanged at D (64) — extension built to current Part L standards; host property retains 1950s solid-wall construction (cavity wall insulation not installed in original construction period; cavity fill survey recommended). Build 14 weeks, within programme. Redbridge Building Control completion certificate issued at week 15.