Building work in Mitcham: area guide

This is our area guide to building work in Mitcham (CR4, Merton): the housing, the council rules that apply (Merton Council for planning) and every service we offer here. For whole-house refurbishment go to Home renovation in Mitcham.

Mitcham is mostly post-war housing, estates and blocks among it, with interwar terraces and semis and a small older core around the Cricket Green and Figges Marsh, and the age groups fail in different ways. What they share is that many have not been touched properly in decades. When we survey a house here the deciding information sits behind the finishes: what the wiring actually is, whether the rear addition has any foundation worth the name, what carries the bay window, and how many previous owners have had a go at the kitchen. Which job you have is only settled by what is found before the design is fixed.

Mitcham's housing, as the Council Tax list records it, is about 10,560 homes: 53% houses, 46% flats, with 10% pre-1919, 38% interwar and 51% built since 1945. VOA Council Tax stock of properties, March 2025, for Mitcham East, Mitcham West and Mitcham South. Counts rounded by the VOA.

What an older Mitcham house gives up when you strip it

Post-war houses here have cavity walls, concrete ground floors and sometimes concrete lintels, so they are opened differently. Open one of the interwar houses and a familiar list appears. Rubber or early PVC wiring still in circuit, an old back boiler flue serving nothing, a bay window on a lintel undersized when built and cracked since, and a rear addition or old conservatory on a slab barely a spade's depth down. All of it changes the scope: the bay lintel is RSJ installation work, the wiring and flue are services. We record what is found, have the structural engineer look at anything load bearing, and agree the revised scope with you in writing before carrying on.

The floors tell their own story. Suspended timber at the front over a ventilated void often meets a solid slab at the back where a scullery was rebuilt, which is why levels rarely match. Airbricks blocked by later paths, patios and render account for much of the damp and joist decay we find. Clearing ventilation, replacing decayed joist ends, insulating the open floor and reinstating a proper damp proof course line change how a house feels far more than a new worktop, and that list is a home renovation, done as one job.

Extending on a repeating plan starts with clay and drains

Because the interwar and post-war plans repeat along the street, a house extension design here can borrow from what has been proved next door, but the ground underneath never copies itself so obligingly. On the shrinkable clay found across much of this part of south London, mature trees near the footprint draw moisture out of the soil and make it shrink and swell with the seasons, so foundations close to them go considerably deeper than a standard trench. The structural engineer sets the depth after trial holes, and the open trench is inspected before any concrete is placed.

Drainage decides the rest of the layout. Rear gullies, the soil stack position and any inspection chamber in the garden all constrain where a kitchen or a bathroom can sensibly sit, and moving them is a job in itself rather than a detail. We survey the existing runs at the start, plan new connections with proper falls and access, and set the addition out so no inspection chamber ends up under a fitted unit, settled before drawings are finished rather than halfway through the build. Rainwater from the new roof needs somewhere to go too, an existing surface water run or a soakaway sized for the area it serves.

Where to go next for work in Mitcham: house extensions in Mitcham, the Merton area guide, building work in Morden, building work in Tooting and Renovation Order of Works.