Yes, for most homes in Ilford you can, though the clay underneath every street will have a say in how. Listed buildings are few and scattered. A handful of conservation areas cover pockets of the town. Hundreds of neighbours apply for planning permission every year. The bigger constraint for most extensions is the ground they sit on.
Ilford has 48 listed buildings: 1 at Grade I, 3 at Grade II* and 44 at Grade II. Any change to a listed building that affects its character, inside or out, needs listed building consent on top of any planning permission, and that covers windows, walls, fireplaces and more. For a town of mostly terraces and flats, 48 is a small number, and the odds that the house you're looking at is one of them are low. If it is, Redbridge Council will take a close interest in more than the extension.
Five conservation areas fall in and around Ilford: Aldersbrook, Durham Road in Manor Park, Romford Road, Valentines Mansion and Wanstead Park. Inside one, demolition and some external changes that would elsewhere go ahead without an application need the council's say-so, and planning officers judge new work against the character of the area. Check Redbridge Council's conservation area map for the exact house, because the boundaries follow particular streets and can leave a terrace on one side of a road inside and the other side out.
Plenty of people do alter their homes. Between April 2024 and July 2026 there were 1,534 planning applications in the area, 613 of them in the latest twelve months. That's a borough used to loft conversions, rear extensions and side returns. In the 1960s the town cleared away a whole mound, Lavender Mount, for building work at the Howards chemical works, and a kitchen extension asks rather less of the planners than that.
The ground needs more thought. The British Geological Survey rates Ilford's shrink-swell hazard at class 3, and every postcode in the area reaches that class. Shrink-swell clay swells when it is wet and shrinks when it dries, so foundations for an extension usually have to go deeper and may need a design that allows for nearby trees. A structural engineer's view on foundation depth is part of planning any extension here. It is a routine extra cost, and nothing to panic about.
Two of the area's listed buildings are on Historic England's Heritage at Risk register. Both are listed buildings in poor condition. Their repair may qualify for grant support and will be watched closely, and they make no difference to the owner of an ordinary terrace nearby.
Outside the conservation areas and away from the listed buildings, many single-storey rear extensions and loft conversions on a house can go ahead under permitted development rights, within national size limits, without a full planning application. Flats have no permitted development rights of that kind, so a flat owner should expect to apply for nearly everything. Inside a conservation area, more work needs an application, and on a listed building nearly every change does.
Ilford gives you a fair amount of freedom: most homes can be extended with standard permissions, and the paperwork only gets heavier in a few protected corners. The clay is the one cost that applies everywhere, so allow for deeper foundations from the start.