[Beepster]

Hey gang. I have questions on building a drop in tub deck for tiling. I am fairly handy. My DIY score is 8.5.


I have never built the framing for a drop in tub. I have the worlds heaviest drop in tub. We are reusing a 66" by 32" cast iron drop in. The bottom has four legs that will sit on the floor.


Q1: On top of the 2X framing I should have plywood (I have 23/32 leftovers), Durock (1/2), and tile on top of that, correct?


Q2: My main question that I can't find online is that when the tub deck is tiled should the top of the tile be EXACTLY the height of the tub? Should I allow for a 1/16 or 1/8 gap to caulk when done? Obviously a tub this heavy is not going to rest on the tile. If I should for exactly and am a bit to high, I assume I could shim the tub legs, correct?


Thanks in advance.


B

 

[Nealtw]

Have never had to deal with cast iron but have built them for acrylic tubs

We build 2x4 walls with plywood top to fit under the tub to share the load with the feet. Concrete board and tile go around the tub flange just like a normal tub at the floor.
If the feet were to cause the subfloor to squash a little you want the surround to take the weight without breaking tile.

 

[Spyder]

We have the below tub, which happens to also be a large 36x66x24 cast iron tub, they don't seem to mention a plywood deck, but just cement board. See the install instructions below. However, I could see the benefit of the plywood deck then cement board. they want the board to go under the lip, but then tile to the lip.

We bought the tub from a contractor and it had a dented corner on the tub deck. bought it really cheap. we then undermounted it with a granite top. we just had framing, no top. Tub is great, we barely use it though, 20/20 we should have just made a big shower.

https://www.us.kohler.com/webassets/kpna/catalog/pdf/en/1084219_2.pdf

 

[Beepster]

Even though it is going to be a tub only that will be used a couple times a year, I think tub over tile will be a cleaner look. If this a Ford/Chevy or Maryann/Ginger debate?


If I am tub over tile, should I shoot for no gap and shim tub legs if needed, or allow for a gap under tub lip that will be caulked?


B

 

[Nealtw]

I would wait for the tile guys to chime in.

 

[Marson]

Even though it is going to be a tub only that will be used a couple times a year, I think tub over tile will be a cleaner look. If this a Ford/Chevy or Maryann/Ginger debate?


If I am tub over tile, should I shoot for no gap and shim tub legs if needed, or allow for a gap under tub lip that will be caulked?


B

Yes, much cleaner to have the tub sitting on the tile. However, no matter how careful and precise you are, you won't get it perfect in any case. So I would build the platform just a speck high, and plan on shimming the tub accordingly. I don't think there's one right answer for gap or not. No gap is nice, but it will likely be hidden by a bead of caulk anyway.

 

[huesmann]

Even if the tub has feet/legs maybe consider putting in a mortar bed to help spread the load and limit settlement potential?

 

[Brother Antioch]

Even if the tub has feet/legs maybe consider putting in a mortar bed to help spread the load and limit settlement potential?

No need for a mortar bed, just put 6" cuts of 6x6 with a metal top plate under each leg. You've now distributed the weight of each leg over 36 square inches, which will dramatically reduce your psi.

 

[huesmann]

Sure, that works, and if you're OK with the additional height it's probably easier. Should be OK for cast iron, but IDT that would work for a different material.