We don't know where you live - here is So. Cal. I don't have a problem with the idea of mold. My homemade ironing board is 24in. by 48 in. covered with 2 layers of cotton batting over a plywood that is 1/2 inch thick. It isn't warping and does not appear to be splitting either. It's now about 9 years old. And I spray my fabric with water instead of steam with the iron and spray starch when I need it. My wool mat is 17 x 24. I hang it up using a plastic clip hanger. But that's mainly to get it out of the way, flat, and readily available.