My house had some foundation issues and the slab inside the house has separated from the foundation wall mostly all around inside the house. Some cracks are about 1/2" and I'm thinking in filling those in before installing laminate flooring. Just to be clear, I'm not talking about the expansion gap between the drywall and the floor, I'm talking about actual cracks in all around the walls in the concrete slab and the foundation. In some parts I can even see the fiber insulation used under the slab.. :(
EDIT: After more research, I found that they call this floating slab and it's done to allow the slab to move because of the expanding soil underneath it, so it doesn't push directly against the foundation and cracks it. My only complaint is that bugs get through it. I wanted to prevent that by rather want to prevent cracks in the walls by the slab pushing against it.