South London architects and chartered technologists

Which South London boroughs do we cover?

Twelve boroughs south of the river, from the dense Victorian terraces of inner Lambeth and Southwark to the interwar and post-war suburbs of Bromley, Bexley and Sutton. The spread matters commercially: the same £840 drawing package covers a Clapham side return and a Bromley hip-to-gable, but the planning route and the neighbour tests differ sharply between them.

What does a typical South London project look like?

The dominant brief south of the river is the ground-floor remodel: a side return infilled, a rear extension pushed back three or six metres, and the kitchen relocated across the full width. It is the single highest-value change available to a Victorian terrace, and it is why the larger home extension prior approval route matters more here than anywhere else in the capital.

That route allows a single-storey rear extension of 6 metres on a terraced or semi-detached house and 8 metres on a detached house, decided in six weeks at £120 after a 21-day neighbour consultation. It applies to houses only, never to flats, and it is withdrawn wherever an Article 4 direction operates — but across the outer South London boroughs it remains genuinely usable.

• Side return and wrap-around extensions in Clapham, Balham, Brixton, Peckham and East Dulwich.
• Hip-to-gable and L-shaped dormer lofts on the interwar stock of Bromley, Bexley, Sutton and outer Croydon.
• Two-storey rear extensions on the larger semis of Merton, Kingston and outer Lewisham, where garden depth allows the 7 metre boundary separation permitted development requires.
• Conservation-area work in Richmond, Blackheath, Dulwich Village and Clapham Old Town, where materials and window proportions carry real weight.

Which South London constraints catch people out?

Three recur often enough to be worth checking before design starts.

• Thames and tributary flood zones — parts of Richmond, Kingston, Wandsworth, Lewisham and Greenwich sit in Flood Zone 2 or 3, which brings a flood risk assessment and constrains floor levels and basement work.
• Tree Preservation Orders — the leafier suburbs of Bromley, Sutton and Richmond carry extensive TPO coverage, and a protected tree within influencing distance of new foundations triggers an arboricultural report costing £400 to £900.
• London clay and mature trees — the geology across most of South London is shrinkable clay. Foundations near established trees are regularly driven to 2.5 metres or deeper, or to a piled solution. That is a building regulations cost rather than a planning one, but it changes the project budget materially.

South London planning questions