I have an acrylic tub that I rough fit into the
area it is to be installed and noticed that when I put pressure onto a corner it tilts about 1/4".
How are these tubs set in place on exposed cement board installations? I heard some put down mortar and then place the tub on that. but I don't know about if that's recommended or not. I could recheck the floor for level, but what if the bottom of the tub is not quite right? Will it stress crack if I just install it as is or is there any "forgiveness" in the flex of these tubs?
Not quite sure what you mean by "exposed cement board installation", but will put my oar in anyway.
I install a lot of baths. About 75% would be acrylic. I always frame up a wooden cradle to support the top edge. That way if someone stands on it, nothing moves. The cradle provides fixing for whatever is used to hide the pipes etc.
For all baths I level the thing in all directions with packers on the cradle keeping it that way. I then remove the bath and spray blobs of expanding foam around the top of the cradle framing and put the bath back.
Then squirt more expanding foam under the thing into the gap of approx 1/2" that was deliberately created for the foam.
This so far has resulted in a rock solid installation with no squeaks.
An acrylic bath can take a fair bit of abuse before it breaks, however the load added when full of water and then a person is pretty large. To be sure and make sure you dont get a complaint later about squeaking........get the thing well supported.
Well, I previously had put down 1/2" durock for preparation of 6" tile installation later...I ran it over the whole plywood subfloor just to make things solid. I just checked and the right rear corner of the left handed tub is about 1/4" (-) low. I just got done leveling it out with self-leveling concrete...it didn't take much.
Now, this tub has a intergal skirt...so I am not sure what you mean by building it up with 2x framing...There's no room for that with the plastic crossbracing supplied on the bottom to suppoort the bottom of the skirt? What do you mean packers Adam? What about all that spray in foam? I have repaired many a door that a homeowner has thought it was a good idea to fill voids with that stuff and it blows out the jambs....wouldn't the same happen in the tub installs?
One of our problems might be understanding each others terminology. I am in New Zealand.
I havent seen a bath with an intergral skirt, so ya got me on that one.
Our acrylic ones have little "ridges" on the underside of the bath to support it. 3 from memory.
Our baths as a norm get dropped into a framed out "box" slightly larger than the body of the bath. This supports it and gives a framework to fix drywall/tiles etc to. This is what covers/hides the side and end of the bath.
The top framing member of the "box" is nailed to the wall on one end and side. The perimeter of this framing is what supports the top edge of the bath. I always make this level but small discrepancies are inevitable. To make the bath sit absolutely level I insert small thin pieces of material in under the bath edge to make it so.
They stay put and the foam acts as a glue to hold it all down.
So far the weight of the bath has resisted any uplift from the foam expanding.
DONT use it on shower trays cos they are not heavy enough and will lift. ( no guesses as to how I know this )
Putting large squirts of foam under the bath holds it down and also makes it feel more "solid" when in use.
My other method is to use construction adhesive to glue it down. A small block of wood glued to the floor and the bath glued to that takes up any larger gaps.
If in doubt as to the foam lifting the thing anyway, I sometimes do the installation in 2 stages. Construction adhesive around the top to glue it down, then a day or so later blast the daylights outa the underside with foam. That works really well. That sucker will NEVER squeak.