Hardie Cement Backer Board Installation Question

[jfh28]

you are not addressing the most critical piece of information for floor tile installation......what is the deflection of the floor joist?....that will be calculated by the clear span of the joist....the joist size......the joist material.....the joist spacing...whether the plumber notched any joists and what size and location of the notches......and whether the bathroom is located on the first floor or the second floor of a residence.....tile is a very unforgiving material when it comes to bending and although you may not notice a 1/4" deflection on the floor the tile sure will......I suspect this is why all the installers are spec'ing 1/2" to get a little extra stiffness to the floor.....installers want to do the job once and be done with it.....the tile manufacturer should have the installation specifications required and you can also look at the tile council of america for their installation handbook......Jack

 

[lennyzx11]

I sure have liked that new lighter advantech board that came out to replace cement backer board.

 

[Tractor Seabee]

I have done several tile floors with embedded heat and quick-set. Always used 1/2" Hardie glued and screwed. Never had a problem w/cracking tile. As was mentioned, 24" joist spacing is iffy for flexing. 24" 2 X 12 joist spacing with 5/4 T&G plywood works well, less starts becoming softer. Older houses; you never know what you will find under the substrates. My current bathroom remodel revealed a large area of dry-rot where shower had leaked int the walls. Wall studs, plates, and plywood floor replacements necessary.

Ron

 

[spitter]

LIke jfh and Seabee said every job is different. 40 years of doing this and I still see stuff that makes me shake my head. cut up floor joists rot bad delaminated plwood {houses built in 70,s had real bad plwood delamination problem]. Old osb swelled up from years of leaking fixtures all have to be addressed before you even think of tileing. Trying to save a few bucks on 1/4 " vs 1/2" ain't going to do u any good when u have cracks in tile down the road. If floor joists r 2 ft oc I would have at least 11/2 "of sub straight . 2 many tile jobs fail from bad prep .:drink:

 

[Cord]

Don't forget to mud set the cement board. You also need to back butter the tiles.

 

[Tompet]

The op corrected specs after initial post. Joists are 16" o.c.

 

[HillStreet]

I have built 4 quality houses fron scratch. 1/4 inch is fine on a 3/4 inch floor with 16” o.c.

 

[mini14]

the 1/4 in floor boards need be applied with a flexbond thinset under them using the correct notched trowel, 1/2in is only used if you need to make up a height difference, otherwise 1/4 is used.

another option Schluter(R)-DITRA & DITRA-XL | Uncoupling (DITRA) | Membranes | schluter.com

 

[tractorshopper]

I prefer the Durock to the Hardee. Easier to cut. Makes a little more mess, but I really like it.