Flooring Tile - Subfloor questions
Doityourself.com community forum was created to provide answers to all questions related to home improvement and home repair. Doityourself community can help you find information about how-to topics on small fixes to large remodeling projects. With comprehensive how-to content and expertly moderated community forums DoItYourself.com makes it easy to tackle even the most complex home improvement projects.View Full Version : Subfloor questions
fallon12345
06-12-05, 04:58 PM
I am redoing my bathroom and I have several questions:
1. I have ripped everything up down to the plywood subfloor, and I have 1 1/4 inches to come up to the hardwood floors outside of the bathroom. I am thinking 1/2" +1/4" backer board should bring me to the correct level. Thoughts?
2. When applying the backer board, HD recommends liquid nails as well as screws. The backer board manufacturer recommends tile mortar.
3. Do I remove the toilet flange, so I can backer board underneath, and then put the flange on top of the backer board? Should I replace the flange?
Thanks in advance, Mike.
1. I have ripped everything up down to the plywood subfloor, and I have 1 1/4 inches to come up to the hardwood floors outside of the bathroom. I am thinking 1/2" +1/4" backer board should bring me to the correct level. Thoughts?
2. When applying the backer board, HD recommends liquid nails as well as screws. The backer board manufacturer recommends tile mortar.
3. Do I remove the toilet flange, so I can backer board underneath, and then put the flange on top of the backer board? Should I replace the flange?
Thanks in advance, Mike.
fallon12345
06-12-05, 05:27 PM
Also, there is a soft spot in the plywood subfloor. Will 3/4" backer board be ok to support it, or should I rip it out and replace it?
Tileguybob
06-12-05, 08:36 PM
1.) Sounds ok to me
2.) They are idiots. The thinset is needed to fill in any gaps, air pockets, voids, whatever you want to call them, between the ply and the cement board, it is NOT there to act specifically as a bonding agent, the nails or screws do that. A ribbon of liquid nails will accentuate the void between layers and that void causes compression of the floor which leads to tile failure.
3.) Not necessary to remove the flange but it will make for easier cuts of the ply and cement board if you can. Otherwise you can buy flange extenders or doubled up wax rings to make up the height difference.
4.) No such thing as 3/4" cement board and CBU doesn't offer structural strength anyway so rip out the rotted piece and patch in with new plywood then go ahead with your plan in #1
2.) They are idiots. The thinset is needed to fill in any gaps, air pockets, voids, whatever you want to call them, between the ply and the cement board, it is NOT there to act specifically as a bonding agent, the nails or screws do that. A ribbon of liquid nails will accentuate the void between layers and that void causes compression of the floor which leads to tile failure.
3.) Not necessary to remove the flange but it will make for easier cuts of the ply and cement board if you can. Otherwise you can buy flange extenders or doubled up wax rings to make up the height difference.
4.) No such thing as 3/4" cement board and CBU doesn't offer structural strength anyway so rip out the rotted piece and patch in with new plywood then go ahead with your plan in #1
Tilebri
06-13-05, 05:37 AM
In your post, question 1, 1/2" ply then 1/4" backer set in unmodified thinset, not liquid nails. Ply should be bc or better exterior grade, screwed to the subfloor only, not the joists and no glueing the layers either.
Replace that soft spot :)
Replace that soft spot :)
Tilebri
06-13-05, 05:42 AM
While we're correcting HD advice, they did not suggest you use anything such as premixed thinset or grout did they? If so, it's a trip to the returns desk. Anything premixed is garbage.
fallon12345
06-13-05, 06:29 PM
Actually, yes. They recommended the premixed mortar. Should I go with the powder? Unfortunately I already bought the 1/2" backer + 1/4" backer, so I am stuck with it. I will replace the soft spot.