Yes, and in most of Castle Green heritage rules won't stand in your way. Listed buildings are few. There's a single conservation area. The neighbours put in planning applications every week. The ground needs more care than the planning rules.
There are 14 listed buildings in and around Castle Green, and none of them is Grade I. Three are Grade II* and eleven are Grade II. Listing protects the whole building, so changes to the inside, outside or setting of one of those 14 need listed building consent from the council on top of any planning permission. An ordinary Becontree terrace is not one of them, and most buyers will never deal with listed building consent at all.
There's one conservation area, at Dagenham Village. Inside a conservation area the council takes a closer look at changes to the outside of a building, and some work that would go ahead without permission elsewhere needs consent there. The council's conservation area map shows whether a particular house is inside the boundary, and outside it those extra rules don't apply.
People here alter their homes all the time. Between March 2024 and June 2026, 688 planning applications were lodged in the area, 292 of them in the last twelve months. The estate was built between 1919 and 1935 to a small set of standard house types, so almost any extension you have in mind has probably been applied for already on a house just like yours. The council's planning register shows what neighbours with the same house type have done, and it's the quickest way to see what has already been allowed.
The British Geological Survey puts the whole of Castle Green at class 3 for shrink-swell ground, meaning clay that swells when wet and shrinks as it dries. For an extension, that means deeper foundations than sandier ground would need and a structural engineer's assessment, especially near trees. It's a known condition that changes the cost of building, and it doesn't stop you building.
One listed building in the area is on Historic England's Heritage at Risk register. That means a historic building in poor condition, which tends to get repair grants and close attention from the authorities. It has no bearing on what the owner of an ordinary terrace a few streets away can do.
In practice, most homes here are unlisted terraces outside the conservation area, so the usual householder rules apply. Some work counts as permitted development and needs no application, and anything beyond those limits goes through ordinary planning permission. Inside Dagenham Village, or on one of the 14 listed buildings, expect more paperwork and a slower process.
Castle Green leaves owners plenty of room to extend and alter their homes. In most cases the planning office isn't the obstacle. The clay underneath is, and that is a matter of foundations.