The 2x6 joists span of 7' 6" is fine for the most commonly used species and grade that I know of. A single 3/4" t&g ply subfloor is adequate too. Both Hardie & Ditra claim even 5/8" is OK. Hardie or Ditra.
Do you know how to install a backer board? Ditra?
TILE GUY - retired- TROY, MI - Method & Product suitability consulting.
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Hey Jaz, thanks for the reply. I have an idea of how each is installed, but I've not yet made up my mind on which one I am going to go with. I've been leaning towards the Ditra though. Hopefully my local lumber supply is open tomorrow.