Trowel notch

[highup]

What's the minimum for 12" tile? Can the notch be smaller if you back butter the tile, or should you always back butter the tile?
Customer has a rental where the guy use a 1/8" trowel and the tile popped off. I think the grout was the only thing holding the tile in place.
Anyway, the owner want's me to install the new tile. There's a 5x5 bathroom, a 3 1/2 foot square entry with an angle cut and an 8 or 9 foot by 13 foot kitchen.
The original backer board is down and she told me they cleaned/smother it out and it's ready to go.
It's Hardi, probably 1/2 inch

 

[DarisMulkin]

If they are porclean tile back butter them. Trowel notch is 3/8v notch if I remember right. I think you also need to dampen the Hardi or it sucks the moisture out of the adhesive.

 

[highup]

More important to butter porcelain than regular tile?
How about regular or modified thinset?

 

[Ernesto]

Always back butter tiles, modified thinset