What the Larger Home Extension scheme covers
Class A of the Town and Country Planning (General Permitted Development) (England) Order 2015 (as amended) allows single-storey rear extensions on dwellinghouses up to 6m projection from the original rear wall (terraced and semi-detached) or 8m projection (detached). The extension must not exceed 4m in height, must not have a balcony or raised platform, and must not contain windows in side walls facing a boundary. The extension must use materials similar to the existing dwelling. Properties on designated land (conservation areas, AONBs, National Parks, World Heritage Sites) are excluded — those still need full planning. Article 4 directions in many London boroughs also remove these PD rights on specific streets.
The 21-day neighbour consultation process
The prior approval process requires the applicant to submit a Class A prior approval application (current fee £120) describing the proposed extension with site plan, floor plan and elevation drawings. On receipt the local planning authority writes to all adjoining owners (sharing a common boundary) describing the proposal and inviting representations within 21 days. If no adjoining owner objects during the 21-day window, the council typically issues prior approval after a further procedural review, with overall determination at 42 days from valid submission. If any adjoining owner objects on amenity grounds (loss of light, overlooking, loss of outlook, dominant impact), the council must assess the impact and may either grant, refuse, or attach conditions. Aesthetic objections (the extension is ugly) are not valid grounds.
Common pitfalls and how to avoid refusal
Three common reasons for prior approval refusal in London: (1) the proposal exceeds permitted PD volume because earlier extensions, outbuildings or roof additions have already consumed the original Class A allowance — always confirm the original 1948 footprint before counting; (2) the property is on designated land or covered by an Article 4 direction removing PD rights — search the council's policy map before applying; (3) neighbour objections on legitimate amenity grounds, particularly on tightly packed terraced streets where the 6m projection creates significant overshadowing of an adjoining garden. To minimise objection risk, talk to neighbours informally before submitting, share the drawings, address light and outlook concerns with the design, and consider modest scaling back at the boundary edge where the impact is highest.
