Yet Another Shower Base Mortar Install Question(s)


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Old 06-04-07, 05:21 PM
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Yet Another Shower Base Mortar Install Question(s)

I am installing a 3 piece (not including door) Sterling Neo-Angle fiberglass shower.

After searching the forum and reading available posts please help me clarify the following points.

1) I will be setting the base in a mortar cement (Quikcrete) bed. Several posts suggest placing plastic down on the subfloor for moisture control during curing, Others have suggested placing plastic ON TOP ot the mortar as well to enable easier base removal in the future.

a) Should I do BOTH, plastic beneath the mortar and on top of the mortar?

b) If I place plastic (3 mil) on top of the mortar will it allow the mortar to "squish" into all of the bracing on the bottom of the base and provide 100% support or will it interfere with the mortar distribution? I would rather have solid support than risk an air pocket that enables base sueaking/cracking.

2) The sub-floor is not quite level and the base must be leveled (raised) about 1/4" on one end. As I understand it, one way to do it is to position and shim the base so that it is level. Mark the wall studs well for easy final placement. Remove the base and place the plastic and mortar down (watching out for the drain hole). Then place the base in position and press it down to the level marks and attach it to the studs. FYI: the sub-floor is 1.5" (3 layers) thick,, don't ask me why.

c) What do I do with the shims that are supporting the front edge/lip of the base?

One poster said it was BAD to leave the front edge (about 1/8" thick) supported by shims. I can see how it would create a stress point. On the other hand, if I remove the shims the front edge that was shimmed will be "hanging" in air while the center portions of the base are supported by the mortar. Of course once the door is in place the one area that might take a users full weight is the rim of the base under the bottom of the door as a user steps in. So I am concerned!

d) Is a 10 pound bag of Quikcrete Mortar enough?

4) I intend to place quarter round molding around the base to trim it out and cover the gap leveling creates.

e) Anyone tried this with success? Does it look OK?

Thank you!
 
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Old 06-05-07, 08:55 PM
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Question Help still needed from noobie!

Hello again,

I could REALLY use some advice on questions A, B and C please.

Anyone?

Thanks!
 
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Old 06-06-07, 04:31 AM
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A) Not a bad idea, on bottom definitely, on top as an option. Have never had to remove a shower intact.
B) 3 mil is fine, and you won't have any air pockets to deal with. The bottom will form the mortar.
C) Cut them off flush and cover with the quarter round you plan on using. After the mortar sets up, the shims will be redundant.

Have you thought of using thinset rather than quickrete? It will probably squish better. And you don't have to fill the entire void with mortar. 4 large dollops will do just fine.
 
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Old 06-06-07, 05:51 AM
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I've installed 3 shower bases in the last year. I used thinset mortar w/o any plastic underneath. I'm not sure it's necessary. I also removed a shower base recently that had been set in mortar. It actually came up fairly easy. Getting the old mortar off the plywood underlayment was a chore though.

If you use wide shims (shingles) to level the base you will be less likely to create a narrow stress point. If your floor is only 1/4" out of level, you might try caulk instead of quarter round. Especially if you have a tile floor.
 
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Old 06-06-07, 07:19 PM
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Thumbs up

Thanks to all for the advice!

I picked up a 25 lb. bag of Master Blend thinset mortar today for setting the base.

I looked for some wide shims (shingles) but could not find any "loose" ones to buy (I only need 2-5 maximum). I will keep looking.

I will probably use a layer of plastic underneath and on top of the mortar bed.

I had to place a screw jack underneath the floor joists as the old support was no longer functioned (cement blocks and shims). As a result I will have have to dry-fit the base and wall sections again and go from there as to the degree of leveling and my trim out options.

Thanks again.
 
 

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