You can, but in South Tottenham you will need permission more often than you'd hope. Most homes here are flats, and flats have far fewer automatic building rights than houses. The surrounding area is crowded with listed buildings and conservation areas. Every postcode is on shrinking and swelling clay. The neighbours keep applying anyway, so it is possible, but it takes paperwork.
The area drawn around South Tottenham holds 207 listed buildings. None is Grade I, 19 are Grade II* and 188 are Grade II. Listing protects the whole building, inside and out, so changing a listed home needs listed building consent on top of any planning permission. That covers new windows, removing walls and even the wrong paint on old brick. Most of these buildings are churches, public buildings and older terraces, but anyone buying one of the Grade II houses takes on the consent process along with the keys.
The same area takes in nine conservation areas, and the box drawn around the district reaches over the borough line. Names such as Clapton Common and Stoke Newington show how far it extends. Inside a conservation area, the council controls demolition and changes to the front of a house more tightly, and work that would be routine elsewhere can need an application. Haringey Council publishes its conservation area boundaries, and checking whether a particular house falls inside one takes about five minutes. Do that first, while the decision is still yours.
People here do apply. The council received 989 planning applications from April 2024 to June 2026, and 481 of them in the last twelve months. Those counts tell you how much building work people here want to do. They don't show how many were approved, and nothing here suggests the council waves them through.
The British Geological Survey places every part of the area in class 3 for shrink-swell, its moderate hazard rating for clay that swells when wet and shrinks in dry summers. For an extension, that means deeper foundations than you would need on stable ground, and a structural engineer's view on how the new section will move alongside the old one. Nobody needs to panic. It does mean the foundations for a rear extension will cost more than a builder from a sandier part of the country would expect.
Fourteen listed buildings in the area are on Historic England's Heritage at Risk register. Those are buildings in poor repair, some of which may qualify for grant funding to fix them, and all of which get close attention from the people responsible for them. For a buyer of an ordinary terrace nearby, they are mainly a sign of how much the authorities are watching in this part of north London.
The practical position depends on what you own. A house outside a conservation area, without a listing, has the usual automatic rights to build some rear extensions and loft conversions without a full application. Even then, a conversion usually needs approval for the design. A flat has far fewer of those rights, and with about 63% of homes on the valuation list being flats, most owners here start from that position. Many of those flats sit in Edwardian houses that were split up, so the freeholder's consent and the lease terms often matter as much as the council's view.
Freedom to extend in South Tottenham is limited. A terrace outside the conservation lines can be extended with the right foundations, but most owners need a planning application, a structural engineer or a freeholder's consent before work can start, and sometimes all three.