Tub "Foundation" Question

[PNW123]

Relatively new lurker who could use some advice on tub design and, more importantly, what to look for and what to stay away from and apologies if I missed a post(s) (I did look...). Original post references "foundation" and what I'm really referring to is the part of the tub that makes contact with the subfloor. We demo'd the guest bath recently at my daughter's house she purchased back in April. Going to install a larger vanity, move the toilet about 10 1/2" closer to the tub and put in a new tub with tile surround. Small bathroom and framed for a 60" alcove tub. Project is hung up because she's having trouble picking a tub and tile. Going to stick with a 30" wide tub to allow max distance to move toilet. UPC in her area and new approximate toilet flange center will be 17" to the vanity and tub and toilet trap will be within 6' of venting. I'm scoped out everything and all looks doable/accessible but going to have a pro come in next week for a look see. We tried to dry fit the first tub she purchased which was a mess because it was long on the length (at least 1/4 and sometimes stronger) and as a result, some of the acrylic busted. This particular tub (well known brand) had 4 2x4 feet fiber glassed (or otherwise attached) to the bottom of the tub which concerned me but never got it in so doesn't matter. Took it back and now she has picked out two more. First one is a reputable brand made of acrylic and has two 2x4 runners that make contact with the subfloor. Second makes contract with the apron and two feet levelers (which I had never seen before and have never heard of this brand). Floor is 1/8" out with the slope running toward the drain. I've been trying to steer her towards something with a solid base on it (e.g. American Standard Princeton) where I could throw down a relatively thin batch of mortar and call it a day but she insists on a square tub design v. oval and I can't find one. With both of these other designs, you are talking about quite a bit of mortar to support the bottom of the tub and the one with feet levelers seems really dicey. What is the best tub design when it comes to making contact with the subfloor and supporting the tub and if we do end up with something akin to 2x4 runners, is it just a matter of a large batch of mortar? Thanks in advance.

 

[Reach4]

If you are not getting a cast iron tub, I suggest you search for posts that have the words pil.es mor.tar (minus the periods). I wrote the words that way because why make this post come up when someone else searches for that words.

 

[Sponsor]

 

[Breplum]

Last times we used Americast tubs, there were warning signs dictating that mortar must NOT be uses under the tub. For those, you must only use ledger board on the back wall.

 

[PNW123]

If you are not getting a cast iron tub, I suggest you search for posts that have the words pil.es mor.tar (minus the periods). I wrote the words that way because why make this post come up when someone else searches for that words.

Thanks. Familiar with the mortar pile method (although admittedly haven't had to do it personally) so I'll check it out

 

[PNW123]

Last times we used Americast tubs, there were warning signs dictating that mortar must NOT be uses under the tub. For those, you must only use ledger board on the back wall.

Thanks. I like the idea of the Princeton (which is Americast with the solid base). I know that enameled steel tubs can have their own set of issues but I'm gun shy at this point about an acrylic tub based on our one run at the dry fit and the chipping (could be cheap acrylic and of course the tub being too long by 1/4"+ didn't help). The Princeton gets good reviews for accuracy of dimensions. In general did you like the Americast, relatively easy to install etc.? I do know it's a bit heavier than acrylic but not much from what i can see. Install directions call for silicon caulk to solve leveling (which means it can't be out much) although the directions on this tub do say that mortar is acceptable.