We're about to lay ceramic tiles throughout the house - having taken on board the good information from the sticky! - but aren't sure whether to also tile the staircases. The stair treads are plywood (I guess the risers also) but I guess subject to more potential movement than the other floor surfaces. Would overboarding with 12mm ply on the stair treads be sufficient to lay ceramic tiles on? or should we really consider some other surface? Also, re skirting boards - is it best to tile up to existing skirting, or remove it and replace on top of the tiles?