Question from a novice if anyone could help please. I am in the process of laying a new slate floor over 18mm ply as recommended. My question is that by raising the floor I will end up with a "step" into the room where I meet the carpet outside. Is this normal and can I buy a carpet retainer to cope with this situation? With 18mm ply and the tiles the new level will be about 7/8 of an inch above the original floor. And if this is normal where can I buy such a retainer as I cant seam to find one on the net. Many thanks.