Voids in mortar under acrylic tub

[Brian]

My brother installed an acrylic one piece tub and surround on the slab. I wasn't there during installation, but they used a mortar bed as often recommended. When we started using the tub, I noticed that there is triangular shaped spot about 4"x8" just off center where you stand to take a shower that is not in contact with the mortar. I'm guessing they placed the mortar anticipating it would spread out more than it did. If I happen to step on that spot, it flexes noticeably under foot. I'm worried that it's going to crack at the edges where it does make contact with the mortar. We've already finished all the walls and tile and the void is toward the apron side of the tub.

Should I be worried about cracking? Should I drill a hole in the tub and fill the void somehow, or drill the apron and home to be able to get stuff int he right place? Just wait and see how it goes?

I'd fire the help, but he is my brother and my electrician so...

 

[Terry]

Common practice is to have piles of mortar and then squish the tub down over it. There will always be voids. It's impossible for it not to have voids.
For mortar to conform, it needs a place to go, otherwise the tub won't sit down in the hole.

 

[Sponsor]

 

[Brian]

Common practice is to have piles of mortar and then squish the tub down over it. There will always be voids. It's impossible for it not to have voids.
For mortar to conform, it needs a place to go, otherwise the tub won't sit down in the hole.

Ok, so nothing to worry about then. That's good. I expected it to be uniformally supported for some reason and the soft spot freaked me out. Visions of tearing out recent work and all that. I won't pay it any mind.
Thanks

 

[Jadnashua]

While coverage won't be complete, the piles, if placed fairly close together, should not have a large void in between them...it will be fairly small. FWIW, some tubs are more robust than others, and that can make a difference in your end result.