Question on mortar under fiberglass tub

[jk1791]

Hello all,

I've spent a good amount of time reading on this forum about this topic but have just a couple questions about using mortar under the tub. Over the weekend I found a crack in my tub and removed the existing fiberglass tub and surround. House is built on a concrete slab. No mortar was under the existing tub. This is an alcove install with limited to no access. As I was reading on installing the new tub most people insisted on using mortar under a new tub. It seems that using piles is the most effective way. My question is, are the piles better than just a bed of mortar? If so, how large (diameter/thickness) should these piles be? This will be a 60x30 sterling ensemble vikrell skirted tub.
Thanks in advance

 

[Terry]

With the Vikrell tub, they should come with a felt pad. If the floor is level, that is often enough.
If the floor is not level, then you may be looking at shimming.

The Sterling tubs can't take too much under the tub. It would not be piles, but maybe some laid down by a deep notch blade which puts some down and some gaps to allow it it spread some when the tub is dropped down.
But that being said, if the floor is level, it may be that you can just drop it down on the felt.