Tiling subfloor advice needed

[b-boy]

This isn't garage related, but I've seen a lot of tiling posts on here. I'm looking for some advice on how to properly handle the entire project. I have a late 1800s house.

My side entryway was tiled. The tile was in pretty bad shape. There was a lot of cracking.

When I pulled up the old tile, I found a 3/4" layer of cement on top of wire lath. Under the concrete was the original hardwood flooring. The lath was not attached to the flooring. It looks like it was laid down and concrete was either poured or troweled on top of it. To me it looks like self-leveling compound. The concrete was badly cracked and probably led to the tile cracking.

I thought about just restoring the hardwood, but there are a few plywood patches that would make next to impossible.

I want to replace the tile in the hallway. Since I'm going over hardwood, I'm planning on doing the following:

• level any low areas.
• Add 1/4" hardibacker over the hardwood. Add screws every 6".
• Add thinset and Schluter Ditra. (unmodified thinset)
• Tile on top of the Schluter Ditra. (unmodified thinset)
• epoxy grout

Questions:

• Any recommendations for tiling over hardwood? I've never done that before. I assume the cracking in the old floor was due to the hardwood movement.
• Do I use thinset below the hardibacker? I've seen it, and done it that way before. The assumption is that it creates a level floor for the hardibacker to sit on and fills and gaps in the subfloor.
• I need to keep the floor buildup to under 1". Will hardibacker, ditra, thinset, and tile do that.

 

[Zippercat]

Best advice I can offer is to go here:

https://www.johnbridge.com/vbulletin/

Go to the Tile Forum/Advice Board. Some great “sticky” threads to read. The pros on that board are very helpful.

Good Luck!

 

[b-boy]

Thanks for the link.

 

[56Mark]

I second JohnBridge. Great advice for tile. If you go with your plan, wet your backer board good with a sponge or it will soak all of the moisture out of your thinset and it won't stick to the fleece on the back of the Ditra. Pull up the Ditra occasionally to make sure it is embedding good. I think you will be very close to one inch of build with your plan. I would put a thin wet layer of thinset under the backer too. Mix the thinset under the backer and under the Ditra much thinner than normal; you want to just barely hold a notch from your trowel. I have put down hundreds of feet of Ditra and Ditra heat and no cracks yet. The oldest job I have done with Ditra is about 15 years old. A couple of other things I think are important; back butter your tile with a thin layer to fill all of the waffle holes or grooves in the tile and try to achieve 100% thinset coverage so there are no voids, use porcelain tile as it is much stronger than the cheap top glazed tiles. I like the laticrete epoxy but hard to find now at Lowes and HD. You can extend the pot life of the epoxy a little by putting the bucket of grout in a bigger bucket containing a little ice water. Mix small amounts of the epoxy grout especially if you haven't used it before. They say don't split the epoxy batches, but using scales I never had any trouble.

 

[MoonRise]

Want tile?

Put in tile.

Properly.

Want hardwood where the old hardwood floor is?

Put in hardwood.

Properly.

Old 1800's house, eh? Check the flooring structure carefully to ensure that the floor framing and the underlayment are up to snuff for whichever floor you want to use.

That era house probably has wood strip underfloor. Which can work for a hardwood floor.

Ceramic tile over hardwood? Generally, no.

The old hardwood should come out, the existing underlayment evaluated for its applicability for use under tile, the subfloor possibly replaced and/or modified, then the tile underlayment (cement backer boards and isolation membrane installed).

https://thefloorpro.com/community/topics/tile-over-hardwood.3185/

https://todayshomeowner.com/how-to-tile-over-a-hardwood-floor/

https://www.ceramictilefoundation.org/blog/ultimate-guide-to-underlayment-for-tile

https://www.diytileguy.com/

https://www.jlconline.com/how-to/interiors/preventing-tile-failures_o

or a whole bunch of other info from a quick google search.

 

[mike93lx]

If you have the room, a good subfloor like Advantech plus a decoupling membrane like ditra should be crack free, as long as you can secure the subfloor properly.

 

[b-boy]

One problem is that there is no subfloor. The 2.5" x 1" tongue and groove pine is the floor and the subfloor. It runs under the interior walls as well. There is blocking in the joists to stiffen parts of the floor. In general, there is no bounce to the floor, but my guess is that there is a lot of movement due to climate changes.

 

[TRWham]

I have been through Schluter training. In your case, they are going to want an additional 1/2" layer over your structural planks. That plus standard Ditra, thinset and 3/8" tile will add a little more than 1" to the subfloor. We always use Ardex X5 as it's good for any Schluter application and costs way less than All-Set. The warranty is better if you use one of the Schluter thinsets, but we have not had an issue and they explicitly approve X5 with a 10 year warranty.

We use more Kerdi than Ditra because we do many, many showers, but I have 3 areas in my own house tiled with Ditra on 3/4" plywood. It is stiff and flat and I would never tile without it. We even use it on concrete slabs to avoid cracks telegraphing through the tile. If the space is large enough, you will still need movement joints.

 

[b-boy]

1/2" layer of wood subfloor, or is 1/2 cement board OK?

Do I screw the subfloor into the joists?

 

[foodie]

Hopefully Dakota will see your post and answer you. If not PM him.

 

[56Mark]

I would not use concrete backer board. It is more waterproofing that structural. Use a good 1/2" plywood. Screw it to the joists. You don't need backer and ditra. It sounds like your floor is probably stiff enough, but there is a link on johnbridge to a calculator to check using joist size, spacing, span.
https://www.johnbridge.com/vbulletin/showthread.php?t=123278

 

[b-boy]

It's a small area, so my spans are only about 5-6 ft. Joists are 16" on center over dimensional 2x8s.

Using plywood makes sense. The concrete that was there before was full of cracks. My guess is that the hardibacker might experience the same stresses.

 

[HDtalk]

The Johnbridge forums are great for tiling. You'll want to double check that your joists can handle the deflection. Look for the Deflecto calculator to see if your 2x8s, 16" oc, and 5 to 6 foot span deflection.



If so, you'll want to install at least 1/2 plywood (BC) underlayment but not into the joists. You want to uncouple the underlayment from the flooring system and that's why you don't go into the joists. Think it goes down perpendicular to the joists and screws are every 6 inches on the edges and 8 inches on the inside of the plywood. Need to double check the screwing pattern and direction though. Then the ditra and your tile.



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[HDtalk]

It's a small area, so my spans are only about 5-6 ft. Joists are 16" on center over dimensional 2x8s.

Using plywood makes sense. The concrete that was there before was full of cracks. My guess is that the hardibacker might experience the same stresses.

It is the total unsupported span of the joist, not the tiled area that has to be taken into account for deflection.

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[TRWham]

Schluter specifies OSB or plywood over structural planks and HDtalk is right about the underlayment installation. Just go find the Ditra installation handbook on-line. It is easy enough to follow and will answer all your questions.