Tile experts - proper subfloor for tile

[allinon72]

This does not concern my garage, but rather my kitchen, but I wanted to get some flooring experts' opinions on what to do to prepare the floor for tile. I have a 1948 house, kitchen floor is old and squeaky. It has 1x6 floorboards (ran perpendicular to the joists), covered by several decades of floor layers, ending with the current floor of adhesive vinyl flooring. The total floor thickness is approx. 1 1/4" including the floorboards. The joists are solid and in good shape, as are the floorboards, but just need to be screwed back down to eliminate the movement as far as I can tell.

Every person on the internet seems to have a different opinion on how to prepare an old house floor properly for tile. I've narrowed down a few options:

1. Take everything down to the joints and install 3/4" T&G plywood, with 1/2" cement board on that, then tile

2. Take existing floor down to the floorboards, resecure the existing floorboards down, install 3/4" T&G plywood over the top of that, self leveling compound over that, then tile

3. Another method I'm not thinking of

What should I do?

 

[Dakota00]

Option 1, is a big job, you could also use 5/8" T&G plywood. Then apply thinset prior to putting down the cement board or use Ditra membrane instead.

Option 2, do not go this route, what ever you do!

As long as the existing floor boards are in good shape. This is what I've done in the past working on older homes.

Remove all existing floor coverings down to the boards. Replace any damaged planks. Screw the rest of the boards down, 2 screws per width of board.

Use 5/8" T&G plywood with PL-400 adhesive, screw down plywood try to hit the floor joists. Prior to placing the plywood down, vacuum the area first and as you proceed so the adhesive can do its job.

Apply Ditra membrane with modified thinset. Ready for tiles!

 

[kd3pc]

we use advantech (or similar product) - glued and screwed on what ever stable flooring you currently have, then thinset with DITRA for the tile job.

The biggest concern is to have subfloor as clean, smooth and stable as possible. If the joists or subfloor move at all then the rest of the process will eventually fail in A few months to a few years later

 

[allinon72]

Remove all existing floor coverings down to the boards. Replace any damaged planks. Screw the rest of the boards down, 2 screws per width of board.

Use 5/8" T&G plywood with PL-400 adhesive, screw down plywood try to hit the floor joists. Prior to placing the plywood down, vacuum the area first and as you proceed so the adhesive can do its job.

Apply Ditra membrane with modified thinset. Ready for tiles!

This seems like the best option, although I'm going to have to deal with some height differences. Thanks for your advice.

 

[rustyjames]

If you want "expert" advice on all things tile you should go to the John Bridge website.

 

[machsnell]

Expert is Dakota. Follow his advice and you wont go wrong.

Sent from my SM-G960U using Tapatalk

 

[Angelfire]

This seems like the best option, although I'm going to have to deal with some height differences. Thanks for your advice.

Will you be too low or too high? I think if too low, there's nothing to say you can't add height using more ply or even cement board.

 

[Radix2]

you never use 1/2in cement board on floors unless you specifically want to raise them.

Cement board has no structural value, so use 1/4 in or as I prefer Ditra type membrane.

your wood structure needs to be sufficient before you get to underlayments

 

[allinon72]

Will you be too low or too high? I think if too low, there's nothing to say you can't add height using more ply or even cement board.

Too high - by about 1/2" or so. But I think I can live with that.

Current plan is screw down floorboards, glue and screw 23/32 T&G plywood, with the Ditra decoupler membrane.

 

[rustyjames]

Have you checked joist material span table for deflection? That's most important part of placing tile on a suspended floor system. I haven't seen this addressed so far in this thread. That's why I recommend the John Bridge site.

 

[allinon72]

According to the John Bridge deflection calculator, I have a deflection of L426, way over the required L360 for ceramic tile. Once the T&G subfloor is added, I suspect that number will increase slightly, and with the Ditra decoupling membrane, I'll be even more good. If I'm mistaken, please someone chime in.

 

[rustyjames]

You're good with the deflection aspect. But from what I recall (from recommendations at JB) is not to use glue on the subfloor, and don't screw that into the joists, as previously suggested. Make sure the your first layer is properly screwed into the joists.

 

[Junkman]

I am not a flooring expert, however, I can tell you what was done in my home 35 years ago, and we haven't had one tile come loose, crack, or any other issues. The plywood floor was screwed down to the joists, and then the installer put down a layer of steel mesh, which he nailed in every direction in a 4 inch pattern. Lots of nails and time to do this, but he said it was necessary to have a floor that would last. He then trowled a layer of cement that was mixed with epoxy over the steel mesh. Once that set up, he came back and started laying the floor. He used a cement that he once again mixed with epoxy, and buttered each time, and set it into place, tapping and working them so they were all level with each other. After he was finished, he grouted the floor, and once again, he mixed the grout with epoxy.
I clearly remember discussing the process with him, since I was paying for all the materials, and it was expensive. He told me that he could skip the wire mesh and put it directly onto the plywood, but warned that it wouldn't last but a few years. Glad that I spent the money to have it done right. I am also glad that I did this when materials were expensive and labor was inexpensive. It seemed like he was working on that floor for 2 weeks. He also tiled the bathrooms, and did the shower floors and walls. He was truly an artist, when it came to tile. He was also a wonderful person, and is missed today by his past clients, friends, and family. RIP Lionel

 

[James-W]

Several years ago I helped a guy I bowled with and his son with their kitchen floor. He a had an older home and the floor squeaked when you walked on it. We ripped out the flooring down to the joists. Once that was done we cleaned off the joists with rags and got them as clean as we could. We put construction adhesive on top of the floor joists and then we put 3/4 inch tongue and groove plywood down. We snapped chalk lines where the joists were located and then we nailed the plywood down with a nail gun using a lot more nails than we really needed to.

After that I have no idea what happened because that was all I helped them with. They had a tile guy stop by and check it out before we did anything and he said to just put down the plywood and he would take care it from there. So that is what we did.

When the tile was down they had me stop by to see how it turned out and I must say it looked really good. Most important, at least to my way of thinking, is that the floor did not squeak at all, it was solid as a rock.

 

[signcrafter]

You're good with the deflection aspect. But from what I recall (from recommendations at JB) is not to use glue on the subfloor, and don't screw that into the joists, as previously suggested. Make sure the your first layer is properly screwed into the joists.

This is correct. When you use two layers of subfloor you do not want to glue the second layer to the first. This will create a bunch of voids between the two since they is no way to get an even layer of glue down. Also when you screw the second layer down you want to only screw into the first layer, not the floor joists.

 

[allinon72]

I understand not screwing the 2nd layer to the joists, to allow for movement via the joists, but what's the harm in using glue since you're screwing into the floor boards anyway? Not getting that part.

 

[rustyjames]

I think if you use a full spread of glue it's ok, but just running a random bead isn't. As signcrafter stated above.