Another Americast tub issue

[kalanikaau]

New residence, I am planning on using Americast tubs. The plumber has suggested setting these in a mortar bed, I am hesitant to do this because the subfloor is plywood (wet cement on plywood does not sound like a good idea), and that AS forbids it. Can anyone tell me why the manufacturer forbids a mortar bed?
I've read Kimby's post here and don't want the same problems with creaking, curiously, the installation instructions say to use roofing nails to secure the tub ledge to wooden studs, but with steel studs to use screws. Nothing doing, I will be using screws even though the studs are wooden.....
Can any experienced plumbers out there offer any other hints or tips with installing these tubs gained from past experiences?
As usual, Thanks in advance !

 

[Krow]

As I understand it, Americast will not warrenty the tub if it is placed on a mortar bed, ......... Why? I have yet to find an answer that makes sense to me. I can't find one.

The object of any tub installation , is to stop the tub, .... or limit the amount of movement of the tub., Whether its up and down or side to side. Screws are definetly the route to take. Before closing the walls, test it, climb in it, fill it with water etc......... and if anything moves or creaks, thats the time to address the problems.

 

[Sponsor]

 

[kalanikaau]

change of plans

Because of Home Depot's liberal return policy I have decided to go with good old (heavy) cast iron tubs. The difference in price is negligible compared to the potential issues later on with Americast.
Luckily the house is just single story, but has 3 bathrooms, all with tubs.
Lucky too that strong (human) lifting power is always available !
Only drawback to this is their seemingly insatiable consumption of that frothy amber liquid...........

 

[Krow]

If I had liberally suggested to place it on a mortar bed, I would have a dozen people telling me how much of a hack I am, so I won't suggest it..........

But I have been doing it for years, since my last creaking issue with Americast. It hasn't failed me yet and the warrenties are still in my favour

 

[Jadnashua]

Someone had indicated that they were worried about bonding the tub could cause it to delaminate. If you were really worried about that, you could put a cleavage layer of plastic over the top of the mortar bed...you could do the same thing on the ply if you were worried about that. The real risk of not putting something on the ply is causing too much moisture to be wicked out of the mortar, compromising its strength, not messing up the ply prior to it curing. Almost all ply these days has exposure 1 or external rated glues, so should not delaminate. Once the concrete cures, there's no problem, either.

 

[Howard M Emerson]

Hi Jim,
As per some other posts I've read hear, I set my acrylic shower base in Structolite that I sandwiched between two layers of 6mil poly. Best of both worlds as far as I can tell: You can pull it up easily if it doesn't come out as you'd like, and no moisture loss to the bare subfloor.

I can't understand why AS and other companies don't suggest this very procedure.

Onward,
Howard