My wife and I recently purchased an older home. The previous owner had replaced the front steps, but there is about a 1/2 inch gap between the side of the steps and our foundation. (the right side of the steps is next to the house). We have water leaking into our basement directly below this spot, and I'm assuming that water is entering through this gap and then settling at the base of the foundation (because I don't know where else it could be coming from). My question is -- how do I fill this gap and effectively seal it so no water can enter it?