RE: VCT Over CutBack
VCT over cutback, I am here in New York City and we come across this all the time. If you can determine the tile and it's the same brand tile (Armstrong to Armstrong) and the previous tile is installed down good you usually can proceed as long as your moisture(RH)/PH readings suffice. It can be a problem if there are loose tiles or an indication of adhesive residue at some of the tile joints then it may be better to demo the tiles and neutralize the old cut back with an approved floor patch(and you RH/PH readings or good.) The last thing you'd want to happen is you cover the old tile and for some reason the old cutback become re-emulsified and it reacts with the new adhesive and then it can be a huge problem. By all means take all the necessary precautions, it's better to be safe than sorry!