Lawful Development Checker — Permitted Development Assessment

A Lawful Development Certificate (LDC) is a formal confirmation from your local planning authority that your proposed work is lawful under permitted development rights. It costs £274 for a householder application (half the £548 planning application fee, from April 2026). While not legally required, it provides certainty and is useful when selling the property.

The total area of ground covered by extensions, outbuildings and other additions must not exceed 50% of the total area of the curtilage (garden). This includes existing extensions, sheds, garages and any other structures. The original house footprint is not counted — only additions since the house was first built (or since 1948).

Semi-detached and terraced houses: maximum 3m rear extension depth (or 6m with prior notification). Detached houses: 4m (or 8m with prior notification). Depth is measured from the original rear wall. The larger extension scheme (prior notification) does not apply in conservation areas, AONB or National Parks.

Yes. Single storey rear extensions: maximum eaves height 3m, overall height 4m. Side extensions: single storey only, maximum height 4m, must not be wider than half the original house. Two storey rear: maximum eaves 3m from boundary, no closer to boundary than 7m. Ridge must not exceed existing house ridge.

In conservation areas (and AONB, National Parks, World Heritage Sites): no side extensions under PD, no cladding, rear extensions limited to standard depths (no larger extension scheme), no roof additions visible from a highway, materials must match existing. Always check with your local authority as Article 4 directions may apply.