I had purchased an ironing board cover with the silver fabric on it. I don't like a cotton top - get's too dirty, soaks up too much water/steam/starch. My silver fabric top had a thin layer of foam on the back that was sticky backed - so it was easy to stick it to my board, wrap the edges around, staple them for good measure, and presto-bango I was done and I can just wipe a damp cloth over the top and it's clean.
The thin layer of foam is THIN, less than 1/4 (perhaps 1/8) and it has just a little give to it, which I like. I don't want a "soft" board for the fabric to "dip" into - I want my fabric to lay as flat as possible. Too much batting/foam and your fabric will sink into the batting. The surface should be flat and for the most part hard.