>is there a radon barrier and is it visible ??
Yep radon barrier was installed as is visible in certain parts
>was the job done by a reputable tradesman the engineer would know or know of , that would help ??
Seems pretty reputable. He's done loads of work (much bigger jobs) in the neighbourhood and like I said .. this was build in Feb last year and no cracks/obvious flaws have appeared.
>have you detailed receipts for all the materials used, are there photos ??
I'm pretty sure I have receipts for all of the materials. I have photos right from the get-go yes.. including the foundation dig, steel fitting, pouring, rought course, radon barrier etc...
Cheers
dudeman