Yes, in most of Chesham, though the old town comes with more paperwork. There are close to 150 listed buildings. One conservation area covers the oldest streets. Neighbours put in close to 300 planning applications a year. The post-war estates take an extension in their stride, while the old town expects to be asked first.
Historic England lists 147 buildings within Chesham: one at Grade I, five at Grade II* and 141 at Grade II. Listing means any change that affects a building's character needs listed building consent on top of any planning permission. That covers alterations, extensions and some repairs, and it applies inside the building as well as outside. Most listed houses are Grade II, and Grade II covers the staircase and the fireplaces as firmly as the front elevation.
Chesham has one conservation area, centred on the old town around Church Street and Germain Street. Inside it the council has more say over demolition, over trees and over changes that would alter how a street looks, and some work that needs no permission elsewhere needs it here. The old town came through the Victorians' improvements largely intact. The conservation area is there to make sure your own improvements meet more resistance than theirs did.
One scheduled monument falls within the area. That is the strictest tier of protection there is, though it only matters if your land is next to it.
Between April 2024 and June 2026, Buckinghamshire Council logged 696 planning applications across Chesham, 287 of them in the last twelve months. Plenty of people here are adding rooms, building on the back and converting lofts, and the planning list is a record of it.
Much of the housing is post-war, including estates such as Chessmount and Hilltop, and most ordinary houses there keep permitted development rights. Those allow modest rear extensions and many loft conversions without a full planning application, within national limits. Flats have no such rights. Listed buildings need consent whatever the size of the job, and a conservation area narrows what counts as permitted. The protected Chilterns landscape also brushes the edge of the town, and development is more tightly controlled there. Ask the council for the house's listing status and whether it is inside the conservation area boundary when you ask for the searches. A semi in Chessmount and a cottage off Church Street are a short walk apart but face very different planning rules.
Your freedom to extend in Chesham is middling. Across most of the town the rules are ordinary, and only the old streets at its heart will make a project slow.