Bathroom Remodel/Americast Tub [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


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07-16-2001, 11:48 AM
I just started a major bathroom remodel and I'm going to install tile for the first time so I will have many questions as I go; some of them will probably seem silly, but I want to do this right. I've ripped out the old shower and I am installing an Americast tub. Someone on one of the forums recommended bedding it in mortar mixed somewhat dry to give it a more solid feel. The house is on a concrete slab. Is this necessary/recommended? John, somewhere you mentioned that you put in a few of these tubs - did you bed them in mortar? Also, when installing either durock or wonder board in the tub surround is it better to use 15lb roofing felt or 4 mill poly behind it as a moisture barrier? Do I extend the moisture barrier all the way to the floor or drape it over the tub flange? Do I leave a gap between the tub flange and the bottom of the durock, sit the durock directly on top of the flange, or overlap the flange, leaving a gap between the bottom of the durock and the ledge of the tub? Thanks.

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John Bridge
07-16-2001, 02:13 PM
Hi Johnnymac, Welcome.

I have not used mud on the Americast tubs. They are pretty solid and install just like a cast iron or steel tub. You nail or screw 2x4 "ledgers" on all three walls. You have to leave out a piece where the overflow comes through.

One thing you may notice is that the Americast tub is a bit lower and slighly wider than the other tubs.

The only time we use mortar is in the case of a fiber glass/acrylic/plastic tub.

I'll leave the backer board question to someone else.

07-16-2001, 06:18 PM
Welcome to the mad-tilers nuthouse.LOL Don't worry about silly questions,you should read some of the stuff we ask each other.
You can overlap the flange stopping the Durock short so it doesn't rest on the tub but this might create a little "kickout" at the bottom.The proper way is to stop the Durock at the edge of the flange and fill/float the rest(about an inch&a half) with latex mod. thinset.This method allows you to keep the wall substrate flat all the way to the tub.

Rob Z
07-16-2001, 06:58 PM

Thanks for visiting the forum. As Keith said, don't worry about your questions. The only one we harass is Art, and he will be along anytime now.

I do set Americast tubs in mud because so many of the subfloors I encounter are really out of level. I set the tub level in a base of mud, then mud the floor in the bathroom, and I'm loving life when it's time to set tile.

As far as the cement board goes, install either poly or roofing felt on the studs and run it down over the lip along the back of the tub. I think the poly is a bit easier to work with, so that's what I have been using.

Keep the cement board 1/4 " off the tub and caulk the gap with silicone to prevent wicking.

Good luck with your project, and come back with more questions.


John Bridge
07-16-2001, 07:14 PM
Hey Rob,

You say keep the cement board 1/4 in. from the tub. Do you mean the tub flange or the horizontal deck of the tub? Seems to me if you go all the way down, the flange (especially on an Americast) is going to bend the backer board inward. Dont' mind me. I'm just an old mud man.

Rob Z
07-16-2001, 08:40 PM

Good point-I should clarify what I said for Johnnymac.

If the tub goes in a perfect opening, then just run the cement board down to the top of the flange. Use silicone as described.

If the studded opening is like I encounter somewhat frequently (and remember I'm not a plumber-I only put in a half dozen tubs a year), then I frequently add lattice to fur the wall for the cement board. Sometimes the opening is greater than the 60" needed for the tub. Sometimes the back or side flange on the tub is not straight, or the tub itself is a little out of square in the opening, or some other situation that results in the need for a little furring action.

The last Americast tub I put in had a flange that got too much of the coating on it, and it was considerably thick at the bottom by the tub (the flange was about 3/8" thick in places.

With furring strips on the wall, the cement board can go down closer to the tub and miss the flange. That's what I was thinking about.


Bud Cline
07-16-2001, 09:59 PM
At any rate you never want to bend the cement board over the flange.

07-17-2001, 06:38 AM
Thanks for the responses. I like the idea of furring out the studs with lattice. Is the lattice you refer to P.T.?

Rob Z
07-17-2001, 06:45 AM

We're glad to help.

No need to use PT material-the poly is there to protect the stud cavity (install the poly over the lattice).