My front porch floor is above the ground level and is made of several concrete slabs. (The size of the floor is about 400 by 70 in). A a same-sized cellar (unfinished) is right under it in the basement. Recently after snow and rain, we found water leaking from the ceiling of the cellar. The leakage spots were exactly located where the concrete slabs meet. So I am sure that the water came from the gap between the concrete slabs. I am wondering if anyone had the same problem and how it was resolved. Thanks.