I think neighbours new building has bridged our damp proof course and blocked cavity wall ventilation

[MGMidget]

I am wondering how serious or common this is in building works and if there is a way to solve it! Our neighbours built a new extension immediately next to our extension wall - both walls now meet at the boundary or thereabouts. There is only a tiny gap between their wall and ours. I shone a torch between the gap the other day and realised that concrete between the two walls is at a level which appears to be higher than our interior finished floor. It looks like they have a smooth concrete foundation running under their wall and adjoining ours and lots of solidified concrete blobs/debris on top of this. Even the smooth foundation under their wall looks too high to be finishing below our damp proof course. What's more we had air bricks/cavity wall weap holes at the lower end of our wall facing towards their side which may now be blocked by concrete. We have some problems developing on our side which was why I was having a look between the walls out of curiousity.

I am wondering if this happens frequently in construction and if so is there a solution that doesn't involve demolishing a property to fix it?!

[dandeliondelilah]

I don't know a solution but I do know that too many builders don't care about this kind of thing. And Mr or Mrs Average you you and I don't realise the implications until it's too late. And with so many people extending out to the boundary, it's going to happen more and more.
Hope you can sort it out ; it's a shame more people don't decide to share the party wall and build one seamless addtion across both houses. Everyone seems to want something slightly different!