Eltham house extensions

Areas we cover around Eltham

Site visits are available across Eltham (DA15, SE3, SE7, SE9, SE12, SE18). We also work in nearby Blackheath (2 miles), Chislehurst (2 miles), Welling (3 miles), Plumstead (3 miles), Catford (3 miles). Just over the Kent border, Swanley is about 6 miles away.

• Blackheath
• Chislehurst
• Welling
• Plumstead
• Catford

Guide prices for Eltham

Every figure below is a guide for Eltham, adjusted for London build costs (×1.3) and including VAT. Design and council fees are shown separately on each page.

Which extension suits a Eltham home?

London's housing is dominated by Victorian and Edwardian terraces, many with a rear outrigger and a side return, and 1930s semis in the outer boroughs. Conservation areas are common, so the planning check comes first.

Start by comparing glass box extensions, wraparound extensions and side return extensions: between them they cover most of the layouts we see requested for houses like these.

Planning and building control in Eltham

In England a single-storey rear extension can usually go up to 3 m beyond the original rear wall of a semi-detached or terraced house, or 4 m on a detached house, without a planning application, provided it is no more than 4 m high, keeps eaves to 3 m within 2 m of a boundary and, with other buildings, covers no more than half the land around the original house. The larger home extension prior approval scheme raises those depths to 6 m and 8 m, with neighbours notified and a 42-day decision.

In England a two-storey rear extension is permitted development only if it projects no more than 3 m from the original rear wall, sits at least 7 m from the rear boundary, matches the roof pitch and uses obscure, non-opening side windows upstairs. Most two-storey extensions therefore go through a householder planning application, which costs £548 from 1 April 2026 and normally takes about 8 weeks.

In a conservation area, national park, National Landscape, the Broads or a World Heritage Site the permitted development limits are tighter (no side or two-storey extensions without an application). Listed homes need listed building consent, and if permitted development rights have been removed, any extension needs an application.

If the work involves a shared wall, building on the boundary, or digging foundations within 3 m (sometimes 6 m) of a neighbour's building, the Party Wall etc. Act 1996 applies and notice must be served before work starts: two months for work to a party wall, one month for new walls on the boundary and for excavations.

Applications are decided by the local planning authority (your district, borough or unitary council).