Mak Wilson wrote:
I don't anticipate floor movement and I've already got the backer board
on hand, so I'll pass on the Ditra for now, but thanks for the thought.

Don't use construction adhesive to put Durock down, use a modified
thinset mortar.

Agreed. The constructive adhesive is only for securing the tub itself
to the (soon to be) Durock floor.

That's usually not necessary. Once it's all plumbed and tiled in, it's
not going anywhere. If it's an acylic tub are you planning on using
something under the floor of the tub to help take the weight?

R