House Extensions Bromley

GS Renovation builds house extensions across Bromley, adding space to the 1930s and post-war semis and detached houses of BR1, BR2 and BR3. We handle everything from foundations and steel to the final fit-out, and we make the generous suburban plots common around Beckenham and Orpington work harder.

In Bromley, a single-storey rear extension typically starts from £40,000, or £2,000 to £2,800 per m² (indicative London ranges, Architecture for London, Resi, MyBuilder and Checkatrade, 2026). GS Renovation Ltd, a building contractor based in Potters Bar, does the work in Bromley: the structural engineer we appoint designs the structure, we build it, and building control signs it off.

Rear and side-return extensions in Bromley

The generous plots on Bromley's interwar and post-war estates suit rear and wrap-around kitchen extensions particularly well, giving the room to add a large kitchen-diner without crowding the garden. On a 1930s semi we often combine a rear extension with the original side passage to create an open family space, installing a steel beam where the back wall is removed and tying the new foundations into the existing ones.

Many single storey rear extensions in BR5 and BR6 fall under permitted development, which means no full planning application, though this depends on the size, the plot and whether the house has been extended before. Larger or double storey schemes, or anything near a boundary, may need planning permission from Bromley Council. We assess your specific property and tell you honestly which route applies before you commit.

Housing in Bromley

Bromley's housing, as the Council Tax list records it, is about 143,450 homes: 67% houses, 33% flats, with 17% pre-1919, 30% interwar and 53% built since 1945. A rear extension on a semi in Bromley digs beside the attached neighbour, so one party wall notice is usual, and 24% of homes here are semi-detached.

How Bromley measures and routes a rear and side extension

Plan a rear and side extension in Bromley as one project, because Bromley charges it as one. For building control charges, the floor areas of extensions built at the same time are added together and measured internally. A single-storey rear addition and a side addition that each look small on their own can together land in the band for over 10 and up to 40 square metres of floor area. That is the band Bromley's schedule uses for a domestic extension with no basement. Measure inside the finished walls, not the footprint on the drawing, before the application is priced.

The route follows the size. Bromley lists the full plans procedure as suitable for extensions or alterations to any building other than small single storey domestic extensions, so a two-storey side addition or a wrap-around belongs on full plans. Planning is a separate question, and Bromley Council states that it is unable to advise informally whether proposals fall within permitted development. A two-storey side addition always needs a planning application. If a single-storey rear part is built at the same time, show it on that application too, so the council assesses the whole Bromley scheme once.

Double storey space on Bromley plots

Where a family needs another bedroom and a bigger kitchen, a double storey side or rear extension makes the most of a wide interwar plot in Chislehurst or Beckenham. We match the new brickwork, roof pitch and detailing to the 1930s original so the addition reads as part of the house rather than a bolt-on, and the engineer we appoint designs the steelwork to carry both new floors safely.

These projects usually need a full planning application to Bromley Council, and often a party wall notice, served by you as building owner, where the extension meets the shared boundary with a neighbouring semi. We manage foundations, groundworks, drainage diversions, the roof and the full internal fit-out, so you deal with one team from the first trench to the final coat of paint rather than juggling separate trades.

Kitchen extensions in Bromley

57% of the houses in Bromley are semi-detached or detached, which usually leaves room for a kitchen extension across the full rear width, with a steel beam over the opening into the house. The fit-out is priced on its own page, kitchen renovation in Bromley; the build figures are in the table above.

• Building control inspections at foundation, damp course and steel stages
• Party wall process explained, and the extension built to the award
• Brickwork and mortar matched to the existing elevation

VOA Council Tax stock of properties, March 2025, for all 39 statistical areas in Bromley. Counts rounded by the VOA.

Work in Bromley rarely sits on its own, so you may also want RSJ and steel beam installation in Bromley, our Bromley area guide, double storey extensions, garage conversions in London, our London house extensions page and Crittall Doors Guide.

The GS Renovation Difference in Bromley

Bromley families choose GS Renovation because we run the whole extension as one project, from the planning or permitted development check through foundations, steel, roof and fit-out. We understand the borough's interwar and post-war houses and their generous plots, plan around the party wall notices you serve, and keep an occupied home liveable. Backed by our founder's 30+ years on the tools.

• Drainage diverted or built over with the right approval in place
• Building control inspected at foundation, damp course and steel stages
• Paperwork and certificates handed over for when you sell

Checked by Abdelaaziz Saaid, founder and director of GS Renovation Ltd (Companies House no. 14611254). Structural design is by the consulting engineer appointed to your project.