One of our recent remodel scenarios involves our local bagel shop. The existing VCT floor was cracking. It had been down for a few years and was installed over plywood. We had intended on removing the existing VCT and installing an additional layer of luan to give the substrate more support and a smoother finish for installation. However, when all the various factors came into consideration we realized several things.
1) If we raised the heights of the floor, we would not have enough clearance for a large heavy walk in refrigerator door.
2) Raising it would also cause the bagel racks to have to go over a ramp or bump. Not ideal.
3) Under counter fridge would not be able to be removed if we raised the level of the floor.
The existing flooring was removed, the sub floor was prepared using a Portland based leveling compound and the VCT was installed directly over the leveling compound.