[irlizard]

Can someone please tell me the procedure for using standard thinset mortar between the plywood subfloor and the hardi backerboard that I will be screwing in so I can lay tile? How thick should it be? What type of trowel? Should it be smooth or have those little ridges like when you lay tile? Should I squish the board down onto/into the thinset or set it gently and how tightly should I screw it down? Wow what a lot of questions! As you can tell I’m new at this so all help is greatly appreciated.

[R&D Tile]

Mix the thinset a little loose, but still stiff enough so that when you spread it, it holds the ridges without collapsing, use a 1/4x1/4" square notched trowel, set the board down on it, walk on it getting it down good, now screw it down tight every 6 to 8" throughout, use the Hardie screws and their square bit that comes in the box, a good corded drill or drywall gun works fine for this, screw it down so that the screws set themselves flush with the board.

Tape and thinset the seams while tiling with a good modified thinset.

[ron schenker]

R&D...the thinset under the Hardiboard should be non modified right? Why shouldn't you use modified?

[R&D Tile]

Some manufacturers say either or, I use unmodified, the thinset is there to just fill any voids between the boards and and the subfloor, not to adhere the boards, that's what the screws are for.

Besides, unmodified is alot cheaper.

[irlizard]

Thanks very much for the guidance and direction. I have grey unmodified for under the board and white latex modified for the seams and laying the tile. I have always used a cordless drill and am not terribly adept with it as a screw driver. I can’t screw straight and I can’t seem to push hard enough. Are these symptoms of the drills inept performance or the operator’s inept performance? Is this why I should use a corded drill and is that OK as a screwdriver?