I had a water leak that caused my kitchen floor to bubble up. When I pulled up the existing floating floor, I noticed that the existing underlayment (cement board) was what actually bubbled up. I unscrewed this board and when attempting to remove it, I discovered 9x9 vinly tiles that were coming up with the board and below the tiles was a black adhesive. My house was built in 1977 so I am assuming that they contain asbestos. Do I need to worry about these tiles being pulled up? What can I do to recover the areas where the tiles are pulled up, since I am not going to remove all the tiles, before laying a new cement board?

 

Use flooring patch to fill in voids left by loose tiles. I am wondering why you are using cement board for an underlayment on a floating floor. Also, explain how cement board "bubbled" up? Usually it is the floating floor that swells when wet.

Minimum 1/2" Plywood or 3/4" Advantech is an excellent base material for your floating floor. There should be a sound deadening material between the new ply and the floating floor. Would totally encapsulate the vinyl asbestos tile that you would never have to worry about it again.

 

I mis-typed, it is not cement board but cement fiberboard which bubbled up or appears to have air pockets that have formed. They seemed to reduce after using a fan to dry them, but still may replace them, if it is necessary.

 

I am replacing the floating floor with ceramic tiles, so decided a cement board was easiest to work with for an underlayment.

 

Durock or Hardiebacker doesn't matter, was the wrong underlayment for a floating floor.

Now, as far as moving forward, we need to determine the stiffness of the floor you have and gauge if it is suitable for ceramic tile. Need the following measurements: Size and spacing of floor joists, length of the open unsupported span of the floor joists, thickness of the plywood under the vinyl tile. That mix will tell us what we need to do to prep the floor for ceramic. May need to add 3/4" plus 1/4" CBU plus tile or can get away with less than 3/4".

Let us know what you find out, we are here to help. Welcome aboard!!!