# ceramic tile on 1x6 boards



## Just Bill (Dec 21, 2008)

The subfloor for ceramic tile MUST be stiff, the usual recommendation is a minimum of 1 1/4" with the top layer being backer board glued/screwed to the subfloor. Without this, you risk having cracked grout and/or cracked or poping tiles. If there is any give to the floor, the tile job will not last.


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## Bud Cline (Mar 12, 2006)

> If we removed that 1/2" T&G,* and laid the durock right on the 1x6 subfloor*, the tile would be very close to the level of the Oak floor.


That would be an expensive disaster. Those type of subfloor slats are unstable and will disrupt the cement board taking the tile with it. PLYWOOD would be required over the slats - a minimum of 3/8" may do the trick. You could then use DITRA for you tilebacker and with the tile you would still be around 3/4"+- above the slats.:yes:

Removing the slats and starting over with plywood as you mention would be an even better deal.


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## thumbs (Jan 30, 2009)

Bud Cline said:


> That would be an expensive disaster. Those type of subfloor slats are unstable and will disrupt the cement board taking the tile with it. PLYWOOD would be required over the slats - a minimum of 3/8" may do the trick. You could then use DITRA for you tilebacker and with the tile you would still be around 3/4"+- above the slats.:yes:
> 
> Removing the slats and starting over with plywood as you mention would be an even better deal.


Schluter uses the term structural planks for the 1x6 subfloor. I called the 1/2" T&G hardwood layer 'slats' - just so we are on the same page...

...you are suggesting removing the 1/2 T&G and laying plywood over the 1x6 'structual plank' subfloor?

the ditra manual suggests that 1/2" ply over planks is ok with joists up to 24" OC. Since the joists here are 16" OC, I would feel comfortable with 3/8" ply i guess.

I am not sure about the ditra yet.. might just go with replacing those 1/2" T&G slats with plywood and then use durock on that, since it is available around the corner and I am not sure where to get ditra for this weekend, as that is when i hope to get at this.


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## Bud Cline (Mar 12, 2006)

> Schluter uses the term structural planks for the 1x6 subfloor. I called the 1/2" T&G hardwood layer 'slats' - just so we are on the same page...


Yow I know I know, toe-may-toe/toe-mah-toe.:whistling2:



> ..you are suggesting removing the 1/2 T&G and laying plywood over the 1x6 'structual plank' subfloor?


I didn't suggest that - YOU DID. I just agreed that it was an option. I wouldn't go to all that work and expense, it isn't necessary.



> the ditra manual suggests that 1/2" ply over planks is ok with joists up to 24" OC. Since the joists here are 16" OC, I would feel comfortable with 3/8" ply i guess.


Good, now we are getting somewhere.:thumbsup:




> I am not sure about the ditra yet.. might just go with replacing those 1/2" T&G slats with plywood and then use durock on that, since it is available around the corner and I am not sure where to get ditra for this weekend, as that is when i hope to get at this.


Gonna need to make a decision!

DITRA is sold at Home Depot. There are two DITRAS available, only one is boasted as working with 24" spaced joists but that's not your concern here anyway.


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## thumbs (Jan 30, 2009)

I still need some clarification...



Bud Cline said:


> Yow I know I know, toe-may-toe/toe-mah-toe.:whistling2:
> 
> I didn't suggest that - YOU DID. I just agreed that it was an option. I wouldn't go to all that work and expense, it isn't necessary.


As to the toe-may-toe/toe-mah-toe... seems we have 2 types of 'slats' here.

I used the term 'slats' in reference to a layer of 1/2"x3" T&G hardwood slats laid perpendicular to the joist over 1x6 structural plank subfloor laid diagonally on the joists.

When I proposed *removing the 1/2" T&G slats and leaving the 1x6 subfloor planks*, noting that if I didn't add plywood the height would be kept close to the adjoining dining room oak floor level, you replied:



> Those type of subfloor slats are unstable and will disrupt the cement board taking the tile with it. PLYWOOD would be required over the slats - a minimum of 3/8" may do the trick. You could then use DITRA for you tilebacker and with the tile you would still be around 3/4"+- above the slats.:yes:
> 
> Removing the slats and starting over with plywood as you mention would be an even better deal.


Correct me if I am wrong again, but it appears to me that since my premise was to have already removed the 1/2" hardwood T&G slats, you are here calling the 1x6 subfloor planks 'slats' and are suggesting that removing even these and laying new plywood direct on the joist would be even better.


My main question was: *is the layer of 1/2" hardwood slats good enough to support durock?* or should I remove those slats (again, leaving the 1x6 subfloor layer) and replace it with 1/2" nom. plywood? IOW, *how would this 1/2" layer of [then] existing hardwood slats compare to 1/2" plywood?*

I didn't elect to remove the 1x6 subfloor plank layer and start over with a modern 3/4" T&G plywood (which is what I interpreted your "even better deal" remark to mean)- though I have done that on other occasions. I note that some feel this is unacceptable since the wall plates sit on the 1/6 subfloor.

We peeled the layer of 1/2" hardwood slats off, and used ringed nails to secure the 1x6 subfloor planks better to the joists. The plan is to sand off a few high spots and then glue & screw/nail 1/2" plywood underlayment over this 1x6 subfloor.

As this is a family freebie, I am getting lots of suggestions from inlaws, some of whom have a little more tile experience than me. I like the idea of Ditra [and I did find my local Home Depot stocked it, TYVM] because it is thin and would help keep the transition between the new kitchen tile level closer to the dining room oak floor level.

None of the inlaws ever heard of Ditra before and question how well the tile/thinset would 'stick' to that plastic and not lift easily. Since my main contribution to this project has been construction and electric, I am more than happy to leave the tiling to them. I just want to provide a solid base for them. But i would also like to learn some and understand the different methods.

As it stands now, we'll have 1/2" plywood underlayment over the 1x6 plank subfloor.

Consensus here is that the Ditra goes back to Home Depot, be it fear of the unknown, resistance to change or valid concerns. I like that it is only 1/8" thick but its not my battle.

That pretty much leaves deciding on either 5/16" or 1/2" Durock. The durock manual indicates the thinner is fine for floors and countertops, and I'd like to keep the total thickness down as much as possible (which is why i had advocated the Ditra). But some say 1/2" is the way to go. Since much of what i have read here seems to indicate thickness of these cement boards doesn't add any stiffness or strength, is there any advantage to using 1/2" over 5/16"?

The next question is what are the acceptable or preferred ways to install the cement board to the plywood underlayment? Modified or unmodified thinset? Roofing nails or screws?

Then, for the tile itself -- Modified or unmodified thinset?

Final question. Should the drywall go on before or after the tile? 'A friend of a friend' says before. But I'd like to keep the bottom edge of the drywall above the tile level, to avoid any water wicking. Any recommendations there?

thanks for your input. its appreciated.


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## 26yrsinflooring (Jul 1, 2008)

I agree with bud on everything except the purchasing Ditra at Home Depot.
You can find it much cheaper from an online surce and you will not have to pay tax.


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