Yes, in most of Feltham, as long as your house isn't one of the handful the council keeps a closer eye on. Listed buildings are few. None of them is Grade I. The conservation areas cover a few roads and a park. Most homes in Feltham are post-war stock that no heritage body has any interest in.
There are 44 listed buildings in and around Feltham, and none is Grade I. Four are Grade II*, the middle tier for buildings of particular importance, and the other 40 are Grade II. Listing protects the whole building, inside and out, so even a modest change to one, from replacement windows to an internal wall, needs listed building consent from Hounslow council on top of any planning permission. Very few Feltham owners will ever have to deal with that, since the town's housing is overwhelmingly from after the war.
The tighter controls come from the 6 conservation areas in the wider area: Bedfont Green, Feltham Town Centre, Hanworth Park, Hanworth Road, Joanna Southcott Chapel and St Dunstan's. Inside them the council looks harder at anything visible from the street, and some work that would be routine elsewhere needs an application. One of the six is named after a single chapel, and some of these boundaries are drawn about that tightly. Check the exact address against Hounslow council's conservation area maps, because the line can fall between two neighbouring houses.
There are 2 scheduled monuments in the area, the strictest level of protection, under which almost any work needs national consent. They matter only if your land is next to one.
People are plainly altering their homes here. Hounslow council's register logged 819 planning applications in Feltham between April 2024 and July 2026, 290 of them in the last twelve months. That is a steady flow of extensions, conversions and alterations from owners who decided against moving.
Three of the listed buildings are on Historic England's Heritage at Risk register, meaning they are in poor condition and in need of repair. That can bring grant funding for their owners and closer scrutiny of any work on them. A buyer of an ordinary house nearby is unaffected.
For most Feltham homes, the starting point is permitted development: the national rights that let householders build some extensions and loft conversions within set limits without a full planning application. Those rights are narrower inside a conservation area, don't apply to listed buildings in the same way, and can be affected by conditions attached to newer developments. Ask the council for a lawful development certificate if you want the position confirmed in writing. A builder's assurance that "you don't need permission for that" carries no weight with the council if a complaint comes in.
Your freedom to extend in Feltham is middling but workable. Ordinary homes get ordinary rules, and the controls tighten in the six conservation areas and around the town's few listed buildings.