Camel

I am currently having an extension built at the moment, and have a question or two after coming home and seeing the progress that was made today.

One of the outside walls is right next door to the fence that divides my back garden and my neighbours. The builder has started the wall in a conventional style, brick on the outside, breeze (sp?) block on the inside....wall ties...damp course all present.

But on the wall that you wouldn't see (from the outside), he has started using breeze block for the outer wall. Is this normal? Safe? Acceptable?

So, is anyone on here a builder....or know about building walls / regulations / best practices etc?

I am happy to talk to him about it, but I just wanted a 2nd opinion first!

Cheers .org!