You can extend a house in Epsom, but you will need permission more often than in most towns. There are hundreds of listed buildings in and around the town. Conservation areas cover large parts of it. All of it is built on clay that shrinks and swells. Neighbours still put in planning applications by the thousand, which shows that people do extend here and that it involves a lot of paperwork.
Historic England's register lists 301 buildings in and around Epsom: 17 at Grade II* and 284 at Grade II, with none at Grade I. Listing covers the inside of a building as well as the outside. Changing a staircase, a fireplace or the windows can need listed building consent, and doing the work without it is a criminal offence, not just a planning matter. A town with this many listed buildings and not a single famous one has heritage that is protected enough to restrict owners and ordinary enough to be next door.
There are 22 conservation areas in and around the town, including Epsom Town Centre, Church Street, College Road, Stamford Green and the Downs Road Estate. In a conservation area, work that would be automatic elsewhere, such as cladding, some roof changes or side extensions, can need full planning permission, and the council looks harder at anything visible from the street. Check the council's conservation area maps and the house's own listing status before doing anything else. A house a few doors outside a boundary can be treated very differently from one just inside it.
There are 3 scheduled monuments in the surrounding area. That is the strictest level of protection, and it mostly matters if your land is next to one.
Epsom's neighbours alter their homes regularly. The council's records show 3,077 planning applications between April 2024 and June 2026, and 1,317 of them were made in the last twelve months. That is a town that wants bigger kitchens and is prepared to fill in the forms to get them. The number shows how much demand there is. It says nothing about how many applications were approved.
The ground needs attention too. The British Geological Survey rates every postcode in Epsom at class three, the highest class found here, on its shrink-swell hazard scale. Clay soils swell when wet and shrink as they dry, so foundations may need to go deeper, and trees near the house need careful thought. Building control will have a view, and a structural engineer should be brought in before the architect draws the extension. The springs that once drew visitors to the Common rose where the chalk meets the clay, and the clay is still affecting what gets built here.
Permitted development, the national rules that let owners make some changes without a planning application, is narrower for flats, more limited in conservation areas and does not cover listed building consent at all. A post-war semi outside the boundaries may manage a modest rear extension without an application. A period house inside one usually cannot. Assume consent is needed until the council confirms in writing that it is not.
The freedom to alter a home is Epsom's weakest point. People do extend here in large numbers, but almost every project involves the council, and the clay adds an engineer to the list.