I’m about to start a tile job for a new house (five baths, two tile floors)
The two floors are in the basement and will be laid on a cement slab. All of the adjoining floors in the basement are to be hardwood. My floors need to be 1 1/2″ above the existing slab so that they will be flush with the hardwood. My plan is to lay two layers of 1/2″ backer board (durarock/permabase). The resulting space will be made up with 1/4″ tile and the thinset for each layer. Any thoughts on drawbacks or alternative methods of building up the floor for the final layer of tile?
Replies
Welcome to Breaktime.
There will be others coming along who can better point you in the right direction, but you might want to consider Ditra. Depending on the area you have to cover, they also make compatible expansion joints.
http://www.schluter.com/english/products/2002/sectionf/overview-f/section-f.html
Total height including thinset is roughly 1/8", so it's not going to add much to your overall height. But it will do a nice job at keeping the tile stable.
Would laying this Ditra layer over backer board be an acceptable solution? I've still got to gain some height.
Yes, you can put it down over backer board or thinset it to the concrete slab itself. That is, if you didn't have your height conditions.http://www.schluter.com/english/products/2002/sectionf/ditra/601-ditra.html#substratesYou might also consider checking out the tile forum at John Bridge
http://www.johnbridge.com/vbulletin/forumdisplay.php?f=1A search through their forum might prove very useful.Good luck.Tua res agitur, paries cum proximus ardet ~ Horace
I think you'll be WAY better off with a 1-1/8" thick mortar bed rather than 2 layers of CBU. No CBU manufacturer will endorse their product for use like that. An alternative might be to pour self-leveling underlayment to the height you need and then tile over that.
One of these rooms is 15X12. Wouldn't the cost of a self leveling mix be extremely high? I don't particulary want to float out another slab
Sounds like you're committed to the backerboard sandwich. Why ask the question if you're not willing to do it right?
No, I'm not committed to the backerboard sandwich. I was just hoping someone would have a viable alternative to floating another floor. I surrender guys..I'll float it!! My very last question...Should I still apply some sort of crack suppressant material over the floated buildup material? Until I go back out and look at the site, I'm not sure if there are expansion joints running through that room. Thanks for your input
My suspicion is this: you probably don't need to do anything other than install a dry-pack mortar bed with wire mesh over the existing concrete, and then tile it. It should span whatever expansion joints are underneath it--that's why it's the best way to do it. The ~1-1/8" you need is fine for a mortar bed.
It's still worth checking at the John Bridge site for their recommendations. I have rarely set tile to a slab, and then only over a crack isolation membrane. The questions you want to ask are: should the mortar go directly over the concrete or not, what is the appropriate wire mesh for this application, should the tile be set directly to the mortar or set over a membrane of some sort, etc. Be prepared with a very clear description of the existing concrete, the tile you want to use, etc., and you should easily get a very clear prescription for the job.
The main thing might be your concern over floating in the mortar. It is basically like playing in a sandbox. It will not set up on you while you are working. As long as you have some height references and some straight screed boards to strike with you will be fine. Getting a really nice flat mortar floor in a small or medium area is quite easy. Just don't be in a hurry.
I would float it. That is use a motor bed.
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