I am seeking to set porcelain tile on top of the hardibacker board once it is secured. If I have to remove the Barmaill plywood, does anyone have any suggestions on how to do this with ease? I assume its glued as well as screwed down.
If plywood is secure, leave it.
I have used a modified thinset to ..... set the cement boards and it didn't stop a crack from forming at a beam. SO I guess what I'm saying is. move on using a GOOD modified thin set mortar. you will be fine. But stuff happens. you are skipping the safety...... but I would live dangerously.
Make sure the plywood is waterproofed by applying a couple of coats of matte polyurethane to it....let it dry completely. Thin set contains water, and you do not want the plywood delaminating. Once the surface is preped, and the plywood is very solid...no flex allowed!, apply thin set and set backer board into it. I usually use drywall screws and screw it down all over the place to make sure the board is in perfect contact with the thinset and backer board. USE Latex fortified thin set or Epoxy thin set...will adhere very well to the sealed ply. NOw, you are ready to set tile...Have a ball. Good luck.
OK... You didn't specify whether you're doing a floor tile job or a wall tile job. If doing a floor tile job, here is the procedure: You can (but don't have to) apply thin set directly to the plywood and then lay and screw down the cement backer board onto the wet thinset. If your floors are pretty firm already, you don't even need to put the thin set on the plywood. Just screw the cement backer board onto the plywood. The thinset makers tell you to put thinset between the plywood and the backer board just to sell more product. It's an unnecessary step if your floors are already pretty stiff. Make sure you screw the backer board down and hit the floor joists underneath with the screws. Screws only going into the plywood is not sufficient. All screws must enter the joists, so get those marked before you start. Use thinset with a notched trowel on top of the backer board to lay the tile into.
Yes, you can use thinset and screws. That is how I would do it, but if the plywood is painted the only thing the thinset will be adhering to is the paint, but if you use a lot of screws it should be fine anyway. They make a special screw especially for cement board called Durock Screws manufactured by USG ( United States Gypsum) and probably by other manufacturers. They make them for wood and metal. You can buy them at a drywall supply store. Durock screws will hold better than regular drywall screws because they have a different type head.
