QUESTION

Floor Preparation - Under the wall to wall carpeting that is there now, the floor is made of three materials. About 4 feet of it is old original 1/2 inch tiles and a large area that is cement (which was used to fill in large gaps of missing tile). What should I do?

ANSWER

ANSWER - As far as your floor preparation, when you are installing tile or stone over different substrates there is a potential problem that the differential movements within each substrate could cause cracking. The best method is to put a cleavage membrane (15lb felt paper) over the existing substrate and then install a wire reinforced mortar bed on top that will be a minimum of 1.25" thick. If you can't go that high, then you could clean, scarify and prime the floor and put a self leveling or trowel-able underlayment down. Then put an anti-fracture membrane on top of that, which you will then thin-set (glue) the tile to the membrane.

 
ANSWER - As far as your floor preparation, when you are installing tile or stone over different substrates there is a potential problem that the differential movements within each substrate could cause cracking. The best method is to put a cleavage membrane (15lb felt paper) over the existing substrate and then install a wire reinforced mortar bed on top that will be a minimum of 1.25" thick. If you can't go that high, then you could clean, scarify and prime the floor and put a self leveling or trowel-able underlayment down. Then put an anti-fracture membrane on top of that, which you will then thin-set (glue) the tile to the membrane.