New neighbours have just informed us they want to convert their loft and that we need to sign a party wall agreement. What should we be considering before doing so? We live in a turn of the century terrace and, over past few months, have noticed an increased number of cracks in walls in various places that have been worrying me. Indeed, when they had their house surveyed, their surveyor wanted to check our side because of a crack on their side - which fortunately it didn't seem to be through to us. My best friend is a surveyor so was going to ask his opinion next time he came over - but this conversion now forces the issue.
My concern is that this terrace - which we know has pretty rubbish foundations - just can't take the few loft conversions that have happened over the past few years. I know that several neighbours have noticed cracks in their properties, so it's not an isolated problem. These may well be nothing to worry about at all - but what rights do I have about making sure that there is nothing to worry about/covering ourselves against any subsequent damage, before letting them have the go ahead?