I hope this is the right place to post this. I am getting ready to paint the walls and floor in the storage area of my basement. The walls are concrete as is the floor. There are a few small cracks where the wall and floor meet and I would like to fill these before I paint. What is the best thing to use here? I don't usually have any leaking issues. Once when we had a flooding rain, a VERY small trickle came in one of the cracks. Thanks!