Prior approval open-plan rear extension

Brief

A 1930s semi-detached house in Palmers Green — the clients wanted a large open-plan kitchen-diner to replace a narrow galley kitchen and cramped rear reception. At 5.5m depth, the extension qualified for Prior Approval under Class A (Larger Home Extension) rather than full planning permission, saving both time and cost.

Challenge

Prior Approval Class A (introduced under the 2013 amended GPDO, extended in 2020 to make the larger-home-extension PD right permanent) allows single-storey rear extensions up to 6m on semi-detached and terraced houses — but requires a neighbour consultation scheme administered by the local authority. Enfield notified both immediate neighbours. One neighbour raised a concern: potential overshadowing to their rear garden seating area. Enfield's case officer requested a sun-path analysis before determining the application. Without one, prior approval would have defaulted to refusal.

Solution

Builderr commissioned a BS 8206-2 daylight and sunlight assessment from a specialist consultant (£650, 5-day turnaround). The report confirmed the proposed extension at 5.5m × 6m (33m²) would reduce the neighbour's rear garden solar access by less than the 2-hour threshold below the BRE 209 guide for a September 21 analysis day. This was submitted to Enfield's case officer, who confirmed the objection could not be sustained as a material planning consideration. Prior approval was granted on day 38 (within the 42-day statutory determination period). Build commenced 7 days later.

Outcome

33m² open-plan kitchen-diner-living zone replacing a 9m² galley kitchen and 11m² rear reception. Layout: kitchen along north wall, central island, dining to south under roof lantern, living zone with bifold to garden. Specification: 3.2m × 2.4m three-panel aluminium bifold (Schuco ADS 75), 1.2m × 2.4m roof lantern, UFH screed (150mm, 100W/m²), Amtico Spacia LVT over UFH. External finish: grey through-colour render to match existing bay render, flat EPDM roof. Building Regulations: Building Notice (not full plans) — appropriate for a straightforward single-storey rear extension, building inspector signed off at completion. Programme 10 weeks from prior approval grant to sign-off.