I made one about 5 years ago - maybe longer, that is the plywood version with 2 layers of cotton batting and and 2 layers of cotton fabric. (It was fabric that my friend already had and we were both making ours together at the same time.) Living in So. Cal. moisture isn't that big of an issue - and there has been no warping or bowing in the wood. Maybe I don't iron as much as you guys - my ironing board hasn't had a problem with dampness.