tiling window sill in shower

Hi there,
I'm in the process of tiling my bath/shower enclosure, and I'm replacing the window in the exterior wall. The window will be high up on the wall and should be out of the path of the water entirely, although it's conceiveable that the shower head could be tilted up to get water on the window. In any case, I am planning on tiling the sill and half way up the window box with mosaic tile. The window is vinyl and will sit on the sill, leaving about 2 inches of sill exposed. I'm going to put up 1/2" concrete board on the wall, so that will add thickness, so say 2 1/2" of sill. I was planning on screwing down a strip of 1/2" concrete board on the sill (over tar paper), slightly sloped away from the window, and then tiling onto that.
Does this sound like it will work?

thanks for any advice,
m

 

Yes, that's a perfect plan for that situation.

 

 

Thats good idea but because of the humidity from the shower you might think about a silicone caulk around the raw edges of the backer board. Avoid any acid based silicone as it might rust any untreated metal...ei. nails, screws. You might also think about silicone around the newly grouted tile after a few days. Home Depot or Lowe's usually carry these items.

 

Even better than silicone in this instance would be a brush/roll on waterproofer over the backer board. You can get a "kit" of a waterproofer made by Laticrete at Lowes for around $50. Sounds like a lot of money, but with it you can make your window area absolutely waterproof. I think it's a great investment. Here's the Laticrete site.

http://www.laticrete.com