You can, but in Kilburn almost every change needs somebody's signature first. Hundreds of listed buildings stand in the area. Over a dozen conservation areas overlap it. Nearly every home is a flat, so the automatic rights that let house owners build without asking mostly don't apply. Kilburn residents put in planning applications at a rate of more than two a day, and they don't do that for fun.
Historic England lists 712 buildings in the area: six at Grade I, 46 at Grade II* and 660 at Grade II. Listing protects the whole building, inside and out, so changes that affect its character need listed building consent as well as any planning permission. Replacement windows, an internal wall or a new staircase can all count. Most of Kilburn's listed stock is Grade II, the most common grade, which still means the council has a say over things most homeowners never think to ask about.
Conservation areas widen the net. Thirteen fall in or around the area, including Alexandra Road, Priory Road, Queens Park Estate, Maida Vale and Fitzjohns Netherhall. Inside one, the council can look at changes to a front elevation, a roofline, a boundary wall or a tree, and works that are routine elsewhere can need an application. Find out from the council whether the address sits inside a conservation area, and whether any extra restrictions apply to that street, because a few doors either way can decide whether a dormer is a formality or a fight.
The neighbours are trying anyway. Between April 2024 and June 2026 the councils covering Kilburn logged 1,926 planning applications for the area, 819 of them in the last twelve months. That is a lot of people asking to change a lot of homes. The volume only shows that people keep trying; it says nothing about how many of them got what they asked for.
The ground needs looking at too. The British Geological Survey rates shrink-swell clay at class 3 across the whole of Kilburn, which means the clay swells when wet and shrinks when dry enough to move a building that sits on shallow foundations. For an extension, that usually means deeper foundations and a structural engineer's design, particularly anywhere near trees. It mostly changes the cost of the build, and it rarely stops one.
Historic England has 24 of the area's listed buildings on its Heritage at Risk register. Those are buildings in poor condition whose repair may attract grant money and will certainly attract scrutiny. For someone buying an ordinary flat nearby, they are no hazard. They are a reminder that the heritage officers here have plenty of work.
In practice, permitted development, the set of changes a householder can make without applying, belongs to houses. Flats don't get it, so nearly every external change to a Kilburn flat needs planning permission, and the freeholder usually has to agree as well. Houses do get it, but conservation areas and listing cut it back. In most of Kilburn, the default answer to "can I just build it?" is to apply first.
Kilburn gives owners very little freedom to change their homes. Buy something that already has the space you need, because adding it later means applications, consents and a long wait.