At times I look at the option of installing a new floor coverings over existing ceramic tile.
New flooring must be installed over a suitable underlayment that is solid, stable, dry, clean and smooth.
Things I take into consideration are:
Is the existing tile bonded well to the subfloor? We can’t install over a old floor unless it is solid and stable. I would look the tile over for signs of bond failure such as cracks in the tile or grout. If I find any cracks I will knock on areas listening for hollow or loose spots. If I find loose or hollow area I would consider removing the tile or at least the loose areas.
Is the tile floor smooth and level? Depending what type of floor you are planning to install need to decide if we can deal with the depth of the grout lines and any uneven tiles throughout the current tile. Any high tiles can be ground down, removed and sometimes floated with flooring patch to a more gradual slope.
If your existing tile is on a wood subfloor? You have an option to install a new wood subfloor over the top. This would raise up the floor even higher.
Also keep in mind all the little things at are effected by raising the floor level. Such as blocking in the dishwasher, is there room above the refrigerator for it to be lifted higher? Will the outside doors still swing in over this new floor?
What will happen at base board areas. Will you lift them or cut to them?
Removing the tile will be hard work, costly, and very dusty. However it is often the best choice in most circumstances in my opinion.