Mud bed for self-leveling whirlpool

[AyUaxe]

I'm putting in a new whirlpool tub (jacuzzi) which has some foam blocks on the bottom of the tub and it is referred to as "self-leveling". There don't seem to be any specific instructions regarding whether a mud bed is necessary for this tub. My first impulse is that a mud bed is always necessary, particularly for a fiberglass tub, but would appreciate the input of those more experienced (I'm just a fairly handy homeowner, fixin' up my old wreck). The floor is well supported, .75 plywood with hardibacker on top. Looking forward to y'all's input. Thanks for all your great help during my lurking period.

[hj]

I could see it being "self evening" to compensate for /even up high spots in the floor, but it would have to be very intelligent to know when it was level and not go past that point and become "unlevel" the other way. Without more information as to HOW it self levels, I would be even more insistent about putting a base under it, because any compressible material would compress even further when the weight of the water and user were placed on it.

[AyUaxe]

Thanks, HJ. As I think and look at it more, the foam blocks on the bottom of the tub would provide a "self evening" function on a level surface with a bed poured around them and up to the bottom of the tub. Add water/weight to the tub after pouring the bed and the foam block "feet" would keep it from rocking out of level or otherwise getting out of position. I'll post further, if I find out anything authoritatively different.

Still soliciting additional comments from anyone with experience setting recent jacuzzi or similar tubs.

[Terry]

The foam is likely fine, as long as the deck is at a perfect height.

The reason most of use use something below the tub, is that it's easier to frame in a little high, throw in a few piles of mortar below, and then let the tub squish them down.

If you're that good, don't worry about it.