: I am installing a Vikrell tub. I have installed cement board for tile and am planning on installing the tub on top of the cement board and the tile up to the edge of the tub.
TTA,

TTA,
Normally, the tub is attached to the studs first, and then the cement board is installed to the studs, to the top of the nailing flange.
Some will shim the walls and install the backer board over the flange, keeping it at least 1/8" above the deck of the tub.

Most of the time, they are installed without support underneath.
I find it nice to put some mortar mix under the tub to reduce flexing. It doesn't take much.
Terry Love

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