I've heard some differing opinions on whether or not I should use an underlayment with my floating cork planks.
They'll be going into my kitchen, over a 100 year old fir subfloor, which is fairly even, although it slopes 1" from one end to the other. Underneath is a basement which, amazingly enough, stays relatively dry - I'm in the SF Bay area.
Do I need some sort of underlayment to prevent any moisture issues (or other issues?) I was planning on DIY the planks directly over the subfloor, & yesterday had a contractor tell me I really needed to use an underlayment......opinions (& more importantly, facts) please?