I've stripped the galvanised garage door and the wooden frame. This has revealed that the base of the frame at each side is rotten. One side has some rough rubbery stuff as filler. I am removing the rotten wood, and putting in some wood hardener. What can I place at the base? It will be between concrete and wood, and the bottom does get damp, so wood is not so good. I thought of some rubber or plastic, but cannot find any. A piece of aluminium strip, bent round and screwed on might do, but I can't find any.