My tile floor is cracking... I want to replace it. When looking at the floor you can see where the floor is unlevel. I went under the house and all the joist are level. It looks like the sub floor is pywood but when putting down the tile before I remember the floor being MDF or something like that.. Is there any way that this subfloor has swollen? What should be done?

MDF is not a good choice for underlay since it is very susceptible to swelling when in contact with water. Rip out the old tile and MDF, if so furnished. Then use hardie or durock over the ply subfloor then your tile.

For best job, remove the MDF as Ma0641 suggested and then install 1/2" hardiebacker cement board in a 1/4" notched trowel bed of thinset mortar on top of the minimum 5/8" plywood subfloor. See instructions at hardibacker website.

Tape the joints with an alkali-resistant tape and screw the sheets down using alkali-resistant screws every 6 inches (every 2" at edges/seams).

Tile with appropriate modified, unmodified, or stone setting thinset as determined by tile choice.

Good luck!

Mark

I'm thinking of doing somekind of floating floor this time. My other question is, the counters are setting on the old tile and are fine. Should I remove them or cut around them? I have some ideas on how to cut around them but if this is OK to do, how would you cut around them?

Suggest a multi-function tool. The better ones can be quite expensive (Fein and Bosch). The Harbor Freight version is quite economical and should serve you needs quite adequately. For best results remove kick board of cabinets if possible. If you install the laminated hardwood flooring and use plywood sheathing, do not install new sheathing tight. Leave about 1/8" gap between sheets and between the old sub floor and new. Glue and screw for best results.

http://www.harborfreight.com/multifunction-power-tool-67256.html?utm_term=67256&utm_medium=cse&utm_source=nextag&mr:referralID=68a6a6eb-401b-11e0-b827-001b2166c62d