I've just layed down the backerboard on a bed of mortar on top of the wood subfloor for a bathroom tileing project. I put in the backerboard screws, but could not get them flush with the board surface (slight raised heads). Home Depot told me that my subfloor is probably partical board and that the screws will not go into that material. I was told I would have to tear it all out and start over with plywood. Please tell me there is another way to have a smooth, flat prep surface for my tiles. Can I pull the screws up and just rely on the mortar adhesive? Or can I mortar over the screw heads, let dry, and then mortar for the tile? Help me please. Thanks.

hkstroud

What kind of screw did you use? There is a special screw for backerboard that has a burr underneath the head of the screw that counter sinks the screw hole as the screw is tightened. Otherwise you will have to counter sink each screw hole before driving each screw.

eschott

I used SuperiorBilt Backerboard screws.

hkstroud

Right screws, how long? Should be long enough to penetrate the wood sufficiently to pull the screw head below the surface. Don't let the screw spin out (enlarge the screw hole so that it has no gripping power). You could remove the existing screws, counter sink the holes and install longer deck screws. If you do indeed have particle board subflooring you will have to be very careful to not strip out the holes. I doubt that you have particle board subflooring.

ballengerb1

You know sometimes the folks at HD are just plain wrong. 1/2" backer uses a 1 5/8 " screw while the 1/4 " board ises a 1 1/4" screw and they both will dig into a particle board sub floor. Why did the screws not set flush, did your drill just bog down or what?

ballengerb1

Thanks a bunch there Art, I see you been doing quite a bit of reading here tonight, enjoy!