You can, but much of Hampton will need permission first. Listed buildings are spread across the town. Nine conservation areas cover the older streets. The ground underneath is clay that moves with the seasons. Plenty of people still get extensions built here, but very few get them built without paperwork.
Hampton has 70 listed buildings. Two are grade I, one is grade II* and the other 67 are grade II. Listing covers the inside of a building as well as the outside, so in any of those 70 even small internal changes need listed building consent from the council, and doing the work without it is a criminal offence. Most buyers will never own one of them. The few who do should expect to explain their plans for a staircase in a great deal of detail.
Hampton also has nine conservation areas, among them Hampton Village, Bushy Park Gardens, Royal Road, Mays Road and High Street Hampton Hill. Inside a conservation area the council takes a closer interest in anything visible from the street, including extensions, roof alterations, cladding and demolition. One of the areas, Platt's Eyot, is an island in the Thames. Another is named after a single building, the Joanna Southcott Chapel. Richmond upon Thames clearly does not think a site needs to be large to be worth protecting.
There is also one scheduled monument in the area. Scheduling is the strictest protection there is, and it only affects a buyer whose land sits on or right next to the monument.
Hampton's residents are hardly short of plans. Richmond upon Thames logged 937 planning applications here between April 2024 and July 2026, 388 of them in the last twelve months. That is a lot of loft conversions, rear extensions and tree works going through the system, so making changes here is clearly normal. The council publishes those applications, and the neighbours read them.
The ground needs some attention. The British Geological Survey puts shrink-swell, the risk of clay soils shrinking in dry weather and swelling in wet, at class 3 in the worst parts of Hampton, and about 53% of the area reaches that class or higher. That is a published hazard class. In practice it means new foundations may have to go deeper, especially near large trees, and a structural engineer should see the plans before the builder quotes for them. It is a cost to plan for, and no reason to call off a purchase. Henry VIII walled off his hunting ground from Hampton Court to Teddington in 1537 without consulting anybody, either about the planning or about the clay.
Six of the listed buildings in the area are on Historic England's Heritage at Risk register. These are historic buildings in poor repair, and their owners may be able to get grants towards fixing them, with close scrutiny of whatever they do. A buyer of an ordinary house round the corner is not affected.
Outside conservation areas and away from listed buildings, many modest rear extensions and loft conversions on houses can go ahead as permitted development without a full planning application. Inside a conservation area, more of the same work needs consent, and flats never had permitted development rights in the first place. Search Richmond upon Thames' planning records for the address to check whether it is in a conservation area and what has already been approved, refused or extended there. The history of a house often tells you how the next application will go.
The freedom to extend is limited here, and getting more space usually means a planning application. The paperwork is mostly about protecting the oldest streets in the town.