If you are going after him on the court, it is not going to be good for you. Plus, the value of the items need to be appraised. You can not get the purchasing value.
不好意思, 你吃了个哑巴亏。
“I think it's the basic knowledge for construction or anyone that if they are going to put a marble shelf on the fireplace, they had to put the support on the bottom due to the weight, but they thought it was not necessary. The entire shelf was held by 5 large nails.”
This is your assumption. The purpose of the table is decorative and not holding items. Without writing, you can not win the case.
Did you get a contractor that is not licensed? If he is licensed, you can complain to the board and if board's decision is favor to you, then you can bring legal action.