Question about Oakey shower drain for tile shower pan

I'm doing an all tile shower (self remodel) and using the basic Oakey shower drain that screws down to tighten agains the tile when done.

My question is with regard to where the bottom flange of the drain meets the subfloor (which is Hardibacker). This is before the mudbed. liner, etc. is put down. Should the botton of the drain be attached to the subfloor in some way? If so, what should I use? Adhesive silicon caulk?

Thanks for your help.

Well, let's backup! While Hardieback is a good choice for walls, it serves no purpose under the mudbed or on the curb. There must be a preslope under the liner so that the liner is sloped to the drain. The drain should have weepholes that you must ensure remain clear when the setting layer is installed. Depending on what's underneath the drain (wooden subfloor or a slab) would determine how thick the mortar needs to be at the low end (it can be thinner over a slab). There are all sorts of ways to make a proper shower, but it is all in the details...doesn't sound like you're getting started correctly. Suggest you check out www.johnbridge.com and look in their 'Liberry' for some guidelines, then ask your questions there. Personally, I prefer a surface membrane verses a conventional shower. My shower of choice is made by www.schluter.com and is made with Kerdi, but there are other methods that work.

I put the Hardibacker on the floor as added support for the subfloor. I'm going to put the pre-slope, etc. on top of the Hardibacker.

So my question is whether the drain needs to be attached to the subfloor (i.e. Hardibacker) before I start the pre-slope work. Thanks.

There is usually no way to fasten it to the subfloor. The weight of the mortar, and being secured to the vinyl liner, will keep it in place.