Bathtub leveling question

[mich5blue]

Hi everyone, I am hoping to get some advice on next steps for a bathtub installation.

Type of tub: American Standard Americast Cambridge (ledger board + apron installation)

The subfloor that is the length of the tub is about 5/8 out of level from end to end, and combined with side to side being another 1/4" out of level I am so far having to shim the low corner up 3/4" - My question is this the best method for doing this?

I was considering using leveling compound once the tub was installed so the tile installation is flat and equal up to the tub, but should I just use leveling compound across the floor including where the apron will be resting on the ground? I was not sure if that would be better vs. apron resting on subfloor + shims.

Thanks in advance for any advice/pointers.

Thanks!

 

[Jadnashua]

The installation instructions call for the tub to be essentially hung from the ledgers and supported by the apron. That's a problem if the floor is not level, as you do want the horizontal surfaces level which means the ledgers must be level and at the proper height and you'd have to shim the apron.

I somewhat disagree with their use of drywall underneath the tile, but that could be okay if it's not being configured as a shower also. Neither the tile nor grout are waterproof, and drywall isn't a good thing underneath tile in a shower unless you use something like Kerdi membrane over it and seal it to the tub. Used in a tub only, you shouldn't get much water up on the rim, and if your sealing job is good, the drywall should stay dry. When the tub is level, any that does get up there should flow back into the tub rather than pool that could soak in. In a shower, though, it could be lots messier.

If you leveled underneath, to get your tile outside to look right, you might need to level the entire room. That may or may not make the transition through the doorway very neat. At a bit over 3/4", a typical tile backer and tile might not cover that at the raised end. If it's a smooth slope, you could make a big shim and support it all along the edge from one end to the other. If you have the tools, you could glue/nail a board there and use something like a power plane to get it level.

I don't know if that tub will flex once it is filled with water and someone is laying or standing in it. If it flexes at all, the general fix for that is to bed the tub in mortar. that also helps to ensure it is level. WIth the ledger boards, you'd just press it down until it touched.

 

[Sponsor]

 

[mich5blue]

The installation instructions call for the tub to be essentially hung from the ledgers and supported by the apron. That's a problem if the floor is not level, as you do want the horizontal surfaces level which means the ledgers must be level and at the proper height and you'd have to shim the apron.

I somewhat disagree with their use of drywall underneath the tile, but that could be okay if it's not being configured as a shower also. Neither the tile nor grout are waterproof, and drywall isn't a good thing underneath tile in a shower unless you use something like Kerdi membrane over it and seal it to the tub. Used in a tub only, you shouldn't get much water up on the rim, and if your sealing job is good, the drywall should stay dry. When the tub is level, any that does get up there should flow back into the tub rather than pool that could soak in. In a shower, though, it could be lots messier.

If you leveled underneath, to get your tile outside to look right, you might need to level the entire room. That may or may not make the transition through the doorway very neat. At a bit over 3/4", a typical tile backer and tile might not cover that at the raised end. If it's a smooth slope, you could make a big shim and support it all along the edge from one end to the other. If you have the tools, you could glue/nail a board there and use something like a power plane to get it level.

I don't know if that tub will flex once it is filled with water and someone is laying or standing in it. If it flexes at all, the general fix for that is to bed the tub in mortar. that also helps to ensure it is level. WIth the ledger boards, you'd just press it down until it touched.

Thanks! I plan to use wedi board as the substrates to put tile on, so waterproofing shouldn’t be an issue.

The floor had concrete as a substrate before which I removed so adding about 1/2 to 3/4 shouldn’t be a huge issue at the transition and I was planning to use ditra membrane which is only about 1/8” for the tile to set on.

I don’t have a planer so I’d likely have to use regular hardwood shims under the apron. The tub doesn’t touch the floor, and wouldn’t even if I didn’t have to shim so I assuming that won’t be an issue with flexing. I’ll look into adding mortar underneath to add some extra strength and reduce the hollow sound when walking on it too. I just was a little worried abut using leveling compound first and have the apron rest on that vs right on the subfloor plus shims (in case the leveling compound cracks or anything)

 

[Jadnashua]

Many shower pans and tubs call for the use of mortar underneath them to help prevent flexing and, if needed, to help level them. This particular one doesn't mention that. If you called them, they would probably say it's okay, and if so, I'd do it that way. Acrylic and fiberglass tubs/shower pans tend to flex some. That can lead to premature failure and prior to that, crazing (microcracks) that will discolor, and eventually break. That can take a long time, depending on how used and how heavy the occupants are.