Welcome! Here are some tips for using this forum.
I have a question on putting a piece of marble on top of my radiators. In books I've seen things about proper radiator enclosures, but the marble radiates heat well, as opposed to wood. I've also saw where thay actually used to manufacture metal rad tops to accept a piece of marble, but I'm not entirely sure if it was meant to sit directly on top or with a gap. So, my question is, would it hinder anything to sit a piece of marble right on top?