Can I apply Leveler right over 3/4" sub-floor?

[R00kie]

Im going to take my circle saw and cut out the vinyl in my bathroom. Going to set my circle saw at 1/4" and cut the 1/4" board that is directly under the vinyl so I don't have to spend all the time scraping the vinyl off.

My question is, can I prime the 3/4" subfloor that remains, apply leveler to that and then install 13" porcelain tiles? It is in a small bathroom. The floor trusses underneath are on 24" centers. Or should I just spend the time and scrap the old vinyl off? Get a little nervous about the height, especially the toilet flange. I would like to put leveler down to make sure everything is good to go when I start to tile.

Thank You,
Brian

[Tool Guy - Kg]

I like removing the 1/4" vinyl underlayment...that doesn't add any structural value to the floor...and it has the potential for causing a liability.

The short answer is: You can do whatever you want. But we highly recommend against your plan to tile over 24" O.C. plywood that has some "leveler" on it. You're going to want a tiling membrane or cement board.

But before going further, we get pretty specific around here with our help. If we can back up for a few seconds to find out about your floor, we can better help you. Tell if there are any other layers besides the 3/4" subfloor. Tell us what each (if any) layer is and how thick it is.

[R00kie]

Trusses underneath are on 24" centers and I would describe as 2 2x4's and inbetween theses 2x4 are a bunch more 2x4's in triangle shapes.

So kind of like this wih 2x4's on top and bottom /\/\/\/\/\/\/\/\/\/\/\/\/\

[Tool Guy - Kg]

Is there anything besides the 3/4" subfloor? Or is that it?

[R00kie]

As it sits right now, 3/4" sub-floor nailed to trusses, 1/4" board and then the vinyl that I want to remove. My concern is like everyone else is height. If I remove the 1/4" board, then apply thinset, 1/4" hardibacker, prime that, then 1/4" leveler, and the 1/4'" tile, I gain quite a bit. It will meet carpet in the doorway, and again, the toilet flange. Not sure how long the extensions are for toilet that I can buy. But get nervous about the transition at doorway. I know there's a company ( I forget name) that sells some nice transition pieces and some pieces even pivot for adjustments to different heights........but if "I Could" lose that extra 1/4", it sure would help, but I do want to do it right. Maybe the floor will be level enoug with just hardibacker, but its nice to dump leveler on it to "be sure".

Thanks Again,
Brian

[R00kie]

If it helps, the bathroom is approx 40 sq ft. A little less when the cabinet i subtracted.

[R00kie]

I was just reading that Fluidmaster has a NO WAX type of flange. Any experience with that? Seems like it can be adjusted to height needed? I like the no wax idea.

Brian

[tileguynky]

Have you put a level on the floor? Is it level? Is the floor flat with no humps or dips? Your floor can be a little out of level and still be good to tile on. Being flat is very important though.

I understand the desire to maintain your height, however the 24" on center is kinda pushing the envelope for a safe sub-floor with only the 3/4" ply and traditional setting methods (backer boards). You need to strengthen the floor to keep the tile from coming loose later on. The self leveler does nothing to strengthen the the subfloor. One way to do that is by adding a second layer of plywood, 3/8" would be minimum. You could then install Ditra from Schluter on top of this floor and you would be about a 1/2" above the subfloor. Another option is you could use 1/4" backer instead of the Ditra. Another option would be to go with the Ditra XL. According to the Installation pdf, Ditra XL is approved for flooring on 3/4" plywood with trusses that are 24" on center. Starting on page 4, it talks about Ditra XL and the testing to use it on 24" on center with tile. On page 5 is the detailed drawing titled, D-W24-XL-T-08. The best part about the Ditra XL, it will raise you about 5/16" above the subfloor plus the thickness of your tile and thinset.

This would be almost like setting your tile directly on you vinyl covered subfloor, which you should not do no matter what. However, you will get an idea of finish height by simply laying the tile on you present floor. As far as the toilet and the height, you can buy longer bolts, longer supply lines, and thicker wax rings to get it back in place and running.