I have a newly built stall shower and I want to make a mosaic ceiling. I have a sheet of hardiebacker 1/4" cut to the size of the shower, and I have my little tiny chips of tile. I was planning to build the mosaic on the board leaving holes in the design for screws. After screwing it to the ceiling over the drywall, I would fill in the mosaic over the screws. I'm wondering if it's a bad idea to put the hardie over the drywall. Should I cut the drywall out of the area and attach the board with mosaic on it directly to the ceiling joists?

Hi Neetie

Glad to discuss the options here. You still around? Let me know as I post daily and am glad to discuss options, OK?

Mark

I'm here Mark and I've got lots of questions! Will 1/4" hardibacker sag on the ceiling? It's 36 x 41. Do I need to put more wood into my ceiling or are the joists close enough together. Do I have to have screws (and wood to sink them into) at the edges of the mosaic or are 2 rows of screws about 1/3 of the way in from each side good enough?

Hi Again

My first thought is for you to simply install the mosaic directly onto the ceiling drywall (without removing drywall)... would give best result, for sure! This is what a professional tile guy would do as the weight of the tile really needs to be supported throughout the area... not just in a few spots, right?

Here, you could kind of draw out the design and then lightly skimcoat the drywall with adhesive and apply the tile in that way. I promise that the tile will NOT fall on you... ;)

I really don't suggest doing it any other way as the weight is too great for a few screws to carry the whole thing. Further, if you install this by putting tile on the cement board you'll have a funny 1/2"-5/8" edge that will need to be dealt with by installing some kind of a finished edge (bullnose tile, tile edgere, etc.).

That's my thoughts for now... glad to continue discussing with you if you want.

Mark