Can I stop my neighbours using their flat roof as an unofficial terrace?

I live on the ground floor of a Victorian terraced house. The house next door has also been split into two apartments and there is an extension at the rear of the ground floor with a flat roof.

The new tenants of the upstairs apartment have climbed out of their windows and are using the flat roof of the downstairs extension as a terrace. They pull out crutches and sit there day and night, and they can see right into our windows and our garden.

I complained to the council, but they said no building permit is needed to sit on an existing roof, is that correct?

MailOnline Real estate expert Myra Butterworth replies: Sorry to hear about your situation as it seems to be causing some inconvenience.

Those who live in built-up areas may have experienced something similar or know someone who has.

But while it may seem like a harmless activity to those using the roof, they may not be aware of the problems it causes, not least for their own safety.

We spoke to an urban planner about the dangers and whether planning permission may be required to use the roof as a terrace.

Regular use of a flat roof as a terrace is a zoning change and therefore requires a planning permit

Martin Gaine, a chartered urban planner, replies: The pandemic has taught us the value of outdoor space, and I sympathize with your neighbors’ desire to use the flat roof outside their window as a place to sit outside, socialize and soak up the sun. They don’t mind climbing out of a window to sit on some stools.

But the flat roofs above the rear extension on the ground floor are usually not suitable as a roof terrace or balcony, as the people sitting on them can look down over the neighbour’s garden and look back at adjacent windows.

Moreover, noise from several people on a terrace on a quiet summer night can also cause nuisance. For these reasons, the planning system is generally quite hostile to informal roof terraces on standard terraced or semi-detached houses.

In my experience, municipalities usually act quickly against illegal terraces, so the reaction of your municipality seems strange.

Regular use of the flat roof as a terrace is a zoning change and therefore requires planning permission.

While no physical development has taken place (they haven’t put railings to close off the terrace and the stools aren’t even permanently there), the use is still illegal.

This unofficial roof terrace can also be dangerous. The roof is probably not designed to support their weight and the absence of railings around the edges makes it unsafe. Since the roof is above the ground floor extension, the new tenants next door are likely to enter by climbing on it.

The simplest solution may be to have a calm conversation with them to explain the issues associated with their use of the roof. It is possible that they will simply stop using the roof once they are made aware of the problems it entails.

Failing that, their landlord (the owner of the adjoining first floor flat) may be able to take action. The owners of the building will also have some authority to act if the use of the flat roof violates the lease of the condo.

Martin Gaine is a chartered urban planner and author of ‘How to Get Planning Permission – An Insider’s Secrets