Q. The other day I was in my basement and noticed a gap between the basement wall and the floor. What would cause that and do I need to worry about it?
A. Well, what would cause this is they pour concrete to make the floor. The concrete has quite a bit of water in it. As it dries, the water evaporates causing "concrete shrinkage". This causes the gap which could be as thin as your fingernail or as much as a 1/2". You can worry about it as much as you want, but there are repairs that can be done.
People repair it is because they don't like the looks of it, radon can come up, insects can come up, also odor can come up from organic material breaking down, and cold air and water vapor can come up. If you have any kind of crack in the basement, you should get it fixed.