Bathtub Mortar Bed

[mmilk_7]

Plumber installed a tub for me (American Standard Studio) and did not use a mortar bed per the manufacturer’s instructions because the subfloor “is solid and flat”. They claim to almost never use them on tub installs (which I know to be true among a lot of plumbers unfortunately). After the fact, I can see that the integral legs on the tub are not fully in contact with the ground near the drain side of the tub (maybe 1/8”) Should this tub get removed and reinstalled with a mortar bed? Second option is to fill the underside with spray foam which I don’t love/trust myself or anyone to do correctly. I have not started any drywall or tile around the enclosure. Thoughts?

 

[Breplum]

Spray foam not good. Mfr's instructions are what to follow. Shoving in mortar with hands and 2x4 will get you somewhere.
First, reach in to that space while someone get in and out of the tub. If it flexes at all, then the tub needs to be redone.

 

[Sponsor]

 

[cdherman]

They DID for a while produce a spray foam version that was higher density. I used it under a shower stall that was flexing a bit. It worked and has held up for 6 years and counting. But I have not seen that product lately. Breplum's suggestions seem reasonable too.

 

[Reach4]

Non-pro idea: could you flood the area with self-leveling compound? https://www.homedepot.com/pep/Henry-555-Level-Pro-40-lb-Self-Leveling-Underlayment-12165/100549588 for example.

Another idea: from below, drill depth-controlled holes, and inject mortar up into the area. Not drilling a hole in the tub bottom is of course critical.