Hi,we just replaced our gas furnace; the new one has been installed in the attic; the old one was in my kitchen inside a closet and part of it was in the ground. It now has been removed, therefore there is a huge 2'X 2' by 2' deep hole in my floor. We want to tear that closet down and even the floor with the rest of the kitchen floor so we can use the extra space. Since the hole is so deep we filled it up with gravel 3/4 up. We want to pour concrete on the top of the gravel to form the slab. Our question is: do we need to put wire mesh on the top of the gravel so the concrete has a grip?, also, do we need to pour the concrete mix up to the level of the other floor? When concrete dryes does it shrink, meaning, do we need to pour more because it will shrink and when it dries it will become lower than the rest? Please advise. We will try to do this this weekend. Thanks for your replies and ideas.