Replies

1. 
   calvin | Apr 27, 2011 06:08am | #1

   Lee

   Of the few Americast tubs I have installed, I cannot remember setting them in anything.  All the support came around the rim and at the base.  Why do you want to do that now?  What did the instructions say that came with the new one?

   We've used structolite under fibreglass units for support.  The steel of the americast shouldn't need that.

   Will it expand?  no.

1. 
   LVelo | Apr 27, 2011 11:55am | #5

   structolite under americast

   My Americast tub is supported by a full length stringer and on the subfloor by it's base.  However, when I stand in the tub, it doesn't feel like the old school cast iron tub i'm used to.  I know Americast is not the same thing as a cast iron tub, but my plumber mentioned that Structolite will greatly help.  I did phone American Standard and they said that an AS tub with that kind of honeycomb bottom would be okay to use a support material.

1. 
   calvin | Apr 27, 2011 12:07pm | #6

   Maybe what I have as an americast

   Isn't what you have.  There was no honeycomb, just the black color of their steel tub on the bottom.  It had two "feet" and the rim support ledger I added.

   If you can get it in there, then I'd add the structolite.

   Best of luck.

2. 
   Dreamcatcher | Apr 27, 2011 07:52am | #2

   LVelo

   Now, I don't know if this is truly "good" or "right", it might not even be applicable but I have a fiberglass tub that was in my house when I bought it. Maybe just because I only owned iron tubs before, the FG tub bottom felt too 'spongey' underfoot. I know that the 'proper' fix would be to reinstall it in a mortar bed or at least attempt to pack in mortar under but I plan to replace this tub in the near future when I remod the whole bathroom. SO, I just used spray foam under and around the tub. I had to use a long extension tube for the foam gun since the only access I had was the backside of the wall behind the shower valve. But the main spongey area was near the drain anyway. 

   It might not be the "right" way but it did the trick and was quicker/easier than mortar. I'm sure removal will be 'fun' later, oh well.

   I am curious what other pros & plumbers think of this.....is it really "wrong" and what are the cons of using foam to set a tub?

   DC

1. 
   DanH | Apr 27, 2011 08:22am | #3

   The main problems are 1) the foam is not that strong, and will compress over time, and 2) as it expands it could potentially lift portions of the floor too high and create puddles.

2. 
   calvin | Apr 27, 2011 08:42am | #4

   DC

   I had the same problem to overcome in a spongy bottomed fibreglass tub.  I had access from below through the 8x14 drain cutout in the subfloor.  I stacked solid blocks  between as I could, then foamed on and around that.  Firmed it up and no thick foam to possibly compress or degrade from movement.  I did fill the tub and stacked two full compound buckets in there to simulate the patrons of the kid bath.

   Worked fine, no problems after.

   Being that velo's tub is a steel with small "feet" (at least the recent americast tubs I've set) and ledger at rim, foam may not benefit.

3. 
   Geoffrey | May 10, 2011 02:06am | #7

   Lee,

   laying plastic(1 or 2 mil) on the subfloor helps with removal of the tub later, if needed, when using a bedding material, Structo-lite and mortars will corrode the metal in a cast/ steel tub, hence the warranty warning. Fiberglass tubs have no such issue with mortar/ structo-lite, so are O.K. I use a setting-type joint compound (E-Z sand 90 ,45, etc. or Dura-bond) for bedding purposes, laying plastic down on the sub-floor, applying the bedding, then setting the tub. The compound is relatively easy to remove from the bottom of the tub , if needed, with a hammer and some well placed strikes.

       I would use the setting compound and not the structo-lite or mortar in your instance.

   You can also use a second layer of plastic on top of the  bedding compound as you mentioned.

   Good Luck,

              Geoff