Flooring Tile - Installing tile in bathroom over plywood?

All-

I'm in the process of removing the existing vinyl floor in a ~70ft2 bathroom. I'm certain that the underfloor is normal 3/4" plywood subflooring. Do I need to put down additional subfloor material or is the plywood sufficient? Also, in the bathroom is a pedestal sink and a toilet, and I understand that any major height changes will require an extended flange for the toilet but am unsure of the sink requirements -- worst case scenario I can think of is that I would have to move the sink mounting bracket, which if just a small amount would be painful...

Any comments, suggestions for the subfloor and height differential???

Thanks-

HMS

Tiling over plywood is okay, but not especially recommended. I recommend 1/4" cementboard. Counting the thinset under it, this will raise the floor only an additional 3/8" or so.

The extension flange (or double wax ring) for the toilet is trivial. Don't give that problem a second thought.

The sink should also not be a problem. The tail pipe connection to the trap should easily accommodate the change in height. Worst case is that you will need to buy a new tail pipe. This might be a good time to swap the supply pipes out for flexible pipe anyway if they aren't already. And as you say, the mounting bracket is moveable. Anyway, the solution to all is easy and inexpensive.

Don't let these problems stop you from doing a quality tiling job. The tile itself will raise the toilet and sink up another 3/8" or so.

So the plywood subfloor with the 1/4" backerboard would be sufficient for the tile job?

HMS

what is joist spaceing, and span. 3/4" and 1/4" might not be enough. the floor needs to meet l/360. someone else will need to take this im heading to the tile show "Coverings"

I haven't measured the joists yet, but will do soon.

What is l/360? I'm not familiar with that -- is that some sort of rule-of-thumb or similar?

HMS

L/360 is a measure of floor deflection. Ceramic tile can only stand so much deflection before the grout and/or tile cracks. If you provide the following information, we can tell you what your floor deflection is, and whether it is suitable for ceramic tile:

(1) Type of joists (probably douglas fir or southern yellow pine) and condition (good or cracked).
(2) Size of the joists (e.g., 2x8, 2x10).
(3) Joist spacing (e.g., 16" on center).
(4) Span in feet between joist supports.

Well, I thought I would give a project update and any pointers that I ran across-

Last week I removed the vinyl flooring with the help of a heat gun, then started scraping up the cardboard/paper backer to the vinyl tile -- man, that adhesive is a b!tch to get up. When I removed all of the remaining backer, then I applied the adhesive solvent and began scraping ( I recommend using a scraper on a long pole.) About 2 applications of the solvent, I have a a fairly stripped floor ready for prep for the 1/4" wonderboard.

Being a small downstairs guest bathroom, I only needed 3 sheets of cement backerboard to cover the entire floor. I cut and dry fitted the backerboard before I began to mix the thinset. I would recommend that you buy a sturdy mixing paddle, as that thinset can get VERY difficult to stir. (I had a poor excuse for a mixer, and ended up helping out with my own hand!) And be sure to sweep/vacuum the area after dry fitting the backerboard, to make sure that you don't have any chunks of cement laying around that will keep the floor from being smooth and level. Now once you apply the thinset to the floor, it is a good idea to have a partner to help manuever the backerboard into position and immediately begin to screw it down. Be sure to drive each screw flush with the surface of the backerboard.

Now last night I began dry fitting the tile (I'm doing a mosaic border of 6" x 12" decorative tile followed by the 12"x12" floor tile in the center) and make all cuts beforehand -- I just completed this part of the project (and I found out that cutting a circular hole in the middle of a single 12"x12" tile for a toilet flange is VERY difficult!!!) and will be begin to mortar the tile in when I get back from Hawaii...

:D :D

I need a break! :) :p

HMS

We actually removed the vinyl flooring prior to installation due to some horror stories I've read at another tile installation boards online and also what happened to friends of ours where they didn't remove their linoleum first and they also used 1/4 Hardi. Now they're dealing with cracks in the grout and a couple tiles have popped out.

Our floor joists are 16" OC. Bathroom tile install had an existing subfloor of 3/4 plywood then we added 1/2 "Durock" in order to firm up the floor as much as possible from any potential bounce. Floor height ended up being a total of 1 1/4 inches. This may be overkill to some but the last thing I wanted was to have to redo a tile job from scratch.

Durock was attached to the plywood with troweled mortor and then those bazillion screws (screwed 6 inches apart and approx 2 or 3 inches from each edge). Used fiberglass mesh tape for all joints and filled with mortor. Let it set for approx a couple days. The floor is very sound with the Durock cement board. We use the same procedure in a second bathroom and yielded the same results. Next, we're moving on to the kitchen.

I totally agree about not mixing up more mortor than you think you'll need because of all of those screws that need to go in. Geez my wrist was so sore afterwards, even though I used a heavy duty cordless drill for driving the scews. Also, something I learned while using Durock, there are special screws that need to be used for cement board. Not sure why exactly.

By the way, I also used the HomeDepot book for tile jobs as a guide, which was ok I guess, but I learned so much more from reading various postings at ceramic tile discussion boards online.