Old but gold, I had the same problem a year ago.
I was trying to move into a new flat but the builder was not showing me the flat itself until I would pay the money and sign the contract. He knew I wanted to came to see the flat with a friend of mine who's an expert in this field and he would definitely find all the weak spots in this construction.
I decided to move forward and not to try my luck with this flat, I've found even a better option, I've bought a used flat, it was pretty new, the previous owner had to move to USA as far as I know, the only one thing I had to do is to change the locks (for my personal security).