DIYbanter - Three-season porch deck tiling.......

Hi all,

I think I have this right..... did a lot of reading.... let me check
with the experts...;-)

I have a 3-season porch (traditional roof, ceiling insulation, and 15
9-pane removable floor-to ceiling windows around the perimeter)
When the house was built, it was a 16'x16' deck (apparently built to
handle a jacuzzi, given the construction beneath, way more than a
traditional deck: multiple 2x10 triple-joist beams and 4x4's, sunk).
The last owner built the roof and wall/windows.

They had 3-season carpet, which I just pulled; the decking is a full 1"
thick PT, covered by 1/4" luaun; joists are 16" oc. I plan on adding
1/2" Hardibacker 500, staggered at right angles to the joists. On top
of that,12" ceramic tiles.

Since this is a 3-season porch, there is significant temperature
fluctuation; from a low of -20F to a high of 110F (it DOES have glass
all around), and there no insulation below; the deck is 7 feet off the
ground, with an enclosed shed below, so the temps fluctate with the
environment. (I am in Southern NH)

So....

Tips/Pointers/Risk factors?

I had done a fair amount of indoor tile, but this pseudo-exterior
temperature-swing environment has me a little concerned..... Any
guidance would be appreciated. Also, am I using the right material? (I
could use 1/2" Wonderboard)

--Paul