One or two layers of Hardibacker 500 under tile?

[Yen]

I'm redoing the shower enclosure around my tub. I'll be using new tile. One layer of Hardibacker 500 over the studs (and over thick plastic) will give me 1/2 inch of buildup and will be flush with the surrounding drywall. The quarter round that I'm going to use on the edges seems to indicate that my base should be 1/2 inch beyond the drywall. Should I use two layers, or one layer over something else, or am I just thinking completely wrong?

The tub is surrounded by three walls. The walls where the tile/concrete board will end are currently standard drywall. Is this OK or should i replace this drywall.

I have already seen the debate on floating a new base vs. concrete board and have chosen concrete board. That is unless someoone wants to come in and float a new base for about the cost and time investment I would spend on installing concrete board myself.

[dogo_01]

I spaced my hardibacker off of the studs by using some cedar strips on top of the studs. I guess cedar is good because it's easy to get and it's rot resistant (the old drywall in the shower was spaced off the studs with cardboard). I certainly wouldn't bother with 2 layers of hardibacker.

I completely replaced all three walls with hardibacker. Obviously the back wall will all be hardi. On the other two walls I would extend the hardi at least 12" past the edge of the tub. My side walls only extended 4" past the tub, so that was easy.

[Randy Calhoun]

Drywall over the studs, then use the 1/2" Hardi over that. Makes a very solid surface and gives the 1/2" you need for the radius trim.

[Yen]

Thanks for the replies. The drywall under does sound stronger. Should I use the green drywall or is there something better?

[Eric Tonks]

[Randy Calhoun]

Yep. That would solider. In most cases when grab bars are installed in an application where backing wasn't installed, 2-3 toggles per flange are most sufficient installed over tile board and drywall or mortar.

[go fish]

Randy Calhoun wrote

I think it would be prudent to follow what the building code stipulates. now's the time to do it right.