Sam Dunn: 'My neighbours are having their loft converted. What are my rights?'

House Doctor

Question: My neighbour has hired a loft conversion company to install a top-floor bedroom in their house, but I'm worried about our side of the dividing wall. The bricks are very loose and if they do damage with steel beams, we can't afford to fix it. We're not the best of friends, to put it gently. What rights do I have? Yv onne Whittaker, Chester

Answer: Love thy neighbour – but not necessarily his loft conversion.

An extra room in the roof has grown increasingly popular over the past couple of years, thanks to looser planning rules and credit-crunch difficulties in securing mortgage finance to move.

In late 2008, planning law changes made it easier to convert a loft: you no longer need permission for conversions that don't exceed a very sizeable 50 cubic metres for a detached or semi-detached home and don't go within 20cm of the eaves.

"Exploiting a loft, which can cost from £25,000 to install, can be a cheap way to create more space," says Gavin Brazg of advice website TheAdvisory.co.uk.

However, it can lead to greater tension between neighbours as building works have a knock-on effect – potentially damaging adjacent walls, roofs and even property structure.

When planning law changes were ushered in, the Royal Institution of Chartered Surveyors warned that disputes could escalate because of "concerns regarding privacy and a loss of amenity".

But while you may not rub along nicely with next door, you've two aces up your sleeve: the Party Wall Act 1996 and his need for your co-operation.

This legislation covers the wall between your two properties that – naturally – you both own and confers responsibilities whichever side of the wall you are on.

Any work which might impact on the structural strength or support of the party wall – or could cause damage to the neighbouring side of the wall – must be notified to a neighbour.

So while your neighbour has a right to a loft conversion – assuming they don't plan to breach planning laws – your shared bricks mean he must also serve notice.

This is usually in the form of an official document provided by the loft company which allows you the opportunity to lodge a dispute.

If you do dispute his notice, he'll have to pay for a surveyor to come in and assess the risk to your side of the party wall.

Show your reasonable nature by simply telling him that you won't dispute his notice as long as he sticks to two provisos.

First, that you take pictures of your wall before and after for comparison; and second, that his loft company repair any damage.

"It's always better to reach a friendly agreement rather than resort to any law," says a spokesman for advice website DIYData.com.