Okay, I think I know the answer to this but I'm asking anyway. Helping my friend remodel his condo and we want to tile the kitchen, dining area and hallways. Much of it was carpet and we ripped it up to find 1/2 inch particle board. The kitchen is also PB with vinyl. We thought to lay vinyl everywhere else to get a smooth transition. But now I'm reading that this might be a "double" no-no. Viny and particle board...are we idiots? He's on a tight budget, which is why we're doing the job ourselves. I told him we should consider ripping everything out and putting down 1/2 inch hardiboard, but that's a few hundred bucks. He's hesitant and would rather just lay it as is. Your thoughts? I figure IF we lay over the vinyl we should at least used acrylic ad-mix in place of water for our thinset, right? BTW, he's remodeling to sell the place, for what that's worth.