Best way to level floor/tub?

I am trying to set a tub unit on a basement concrete floor which is nearly level, within 1/2 inch from end to end. The tub is an acrylic product with feet on the bottom and a cross-hatched grid of support stringers between the feet. The directions say to lay a 2 inch mortor base under the tub, but I am not sure I could make that anymore level, nor do I want to raise the tub 2 inches. It also suggests to put a layer of landscape fabric under the tub to keep it from squeaking against the concrete. The tub apron is connected to the base of tub by a support, so the apron must not be strong by itself.

My questions are:

Do I have to level the floor precisely?
Can I use another product besides mortor to level the floor that self levels and what would an example of that be?
Could I use the expanding foam spray underneath? Or is mortor better? How do I keep the tub level when setting it in this stuff when wet?
Or is there another way I haven't even thought of?

Dave Pierce

Run a ledger board (2 x 4) on inside edge of tub, find the level height on the tub with level, attach the ledger to the height needed, the inside edge will rest on this ledger, run SS screws around the perimeter of the tub lip into the stubs in the wall surround.

You can foam the underneath, but before you use foam, fill tub full of water to keep tub from lifting up when form does expand. Let foam set for good 24 hrs, before you let water out of tub.

If you use the mortar, you set the tub down in it while it is still wet and "smush" it until it is level. The 2" give you enough to fill in the openings and have some ability to level it. The actual height gain may not be much of anything, depending on how far you smush it down. This gives you a very firm base. I'm not a pro, but I don't think I'd want the tub hanging by the lip with water in it. The foam should work fine after it is set up, but until then, it seems a little scary to me.

I'm not a big fan of a foam base under a tub. As was said previously, you set the tub in the mortar bed (I use Sakrete sand mix) while its wet. Also, 1/2" out of level really isnt "nearly" level especially when talking about a 5' run.