I have a client that is interested in putting 13″ Ceramic tile on their kitchen floor. The joists are 2×8 16o/c w/ 3/4″ subfloor. I was planning on using 1/4″ (should I use 1/2″?) hardibacker. Is there any concerns about floor movement (it does slightly) and cracked tiles?
I install tile but i’m certainly not a “tile guy”.
Replies
You don't call out the span.
1/2" fer sure.
Spheramid Enterprises Architectural Woodworks
"Yup, I really bought this place, wanna shoot me? Please?
I figured you'd need that. The room is only 8' wide but I believe the span is 10-12 feet.
Threshold city...go half inch for sure.
Spheramid Enterprises Architectural Woodworks
"Yup, I really bought this place, wanna shoot me? Please?
He wants the floor transition as level as possible but sometimes what can you do. So you dont think there will be any crack problems? I guess I can use Ultra Flex (I think thats what its called).
Thanks
It doesn't matter if you use 1/4" or 1/2" or 1" hardiebacker ... it won't do anything for the strength of the floor. All it does is give a good bnonding surface and additional thickness. If you're concerned about cracking, a proper membrane will help, or additional plywood glued and screwed.
I'm sorry, I thought you wanted it done the right way.
Ed, I'm aware that hardi isnt structural. Could you elaborate on the membrane?
I dont think the extra ply will fit height wise, it would create too great a transition.
You mentioned in your first post that there is some deflection, so that needs to be considered.
Having brain lock right now ...I get a membrane from DalTile that is actually made by _____ as a private brand. It's a non-woven rubberized fabric that is set in a bed of thinset, then the tile is set in another layer of thinset. It adds almost zero thickness but helps to prevent cracking. That might allow you to add a layer of underlayment grade plywood to help stiffen the existing floor.
I'm sorry, I thought you wanted it done the right way.
I don't see how a membrane could help prevent cracking if there is inadequate stiffness in the floor framing. My understanding of the anti-fracture/cleavage membranes if that they help prevent localized cracks in slabs from telegraphing thru the tile, by making the bond to the slab weaker than the bond to the tile.
This is not what I used, but it might work for you. Look at the second sentence in the last paragraph.
Application and Function
Schlüter¯-DITRA is a polyethylene membrane with a grid structure of square cavities, each cut back in a dovetail configuration, and an anchoring fleece laminated to its underside. Designed for ceramic tile and dimension stone installations, Schlüter¯-DITRA serves as an uncoupling layer for problematic substrates, a waterproofing membrane, and a vapor pressure equalization layer to accommodate moisture occurring at the underside of the substrate. To bond Schlüter¯-DITRA, use a bonding mortar that is appropriate for the substrate. Apply the mortar using a 1/4" x 3/16" (6 mm x 4.5 mm) V-notched trowel. The anchoring fleece on the underside of Schlüter¯-DITRA must be fully engaged in the mortar to provide a mechanical bond to the substrate. Using the thin-bed method, set the tile covering directly on the Schlüter¯-DITRA in such a way that the tile adhesive becomes mechanically anchored in the square, cut-back cavities of the Schlüter¯-DITRA matting. Schlüter¯-DITRA is also suited as a support matting for covering materials such as stucco, plaster, or screed. NOTE: For installation information on the earlier “corrugated rib” design of Schlüter¯-DITRA, please contact your Customer Service Representative.
Summary of Functions
a) Uncoupling Schlüter¯-DITRA uncouples the floor covering from the substrate and prevents the transfer of stresses to the tiled surface. Thus, stresses caused by deformation of the substrate are neutralized. Likewise, stress cracks in the substrate are bridged and are, therefore, not transferred to the surface covering.
I'm sorry, I thought you wanted it done the right way.
Hardi is not structural.Regards,
Boris"Sir, I may be drunk, but you're crazy, and I'll be sober tomorrow" -- WC Fields, "Its a Gift" 1934
I got the deflection by bouncing all 224lbs of myself on the floor. We noticed the fridge moving a bit.
I've already told this guy that without beefing up the joists cant promise anything as far as cracking.
I seriously dont expect any cracked tiles a guess i'm more concerned about grout failure.
what is the span of your floor joists?
I believe the span is 10-12'. The room is about 8' across(parallel to the joists).
http://johnbridge.com/vbulletin/deflecto.pl
Try using that.
If you have a 10' span you should be fine if you have a 12' span you need to beef up the framing for less of a deflection before you can tile.
Like has been mentioned, Hardi will not add any signifigant structural strenght.