Which Mortar for Bed for One-Piece Maax Fiberglass Shower?

[kailor]

I'll be installing a Maax S-42 one-piece fiberglass shower this weekend (42" x 36"). After dry-fitting the shower into alcove, I want to set the unit in a bed of mortar (not structolite). Which mortar product (by exact name and amount please, if possible) should I use that is readily obtainable from a Big Box Store? This will be on 3/4" plywood subfloor (which I'll reinforce). I have access to both sides of shower, but not back wall. Also, please comment on my plan of attack.

1. Frame alcove, cut area in subfloor for drain
2. With unit on its side, determine approximate depth of mortar bed
3. Dry-fit unit, level unit, mark lines, locate shim areas, etc.
4. Roofing felt on plywood subfloor
5. Apply mortar bed on roofing felt
6. Apply 3-mil plastic over mortar bed
7. Set unit
8. Level/plumb as I screw nailing (oxymoron) flanges to studs (back top flange, side top flanges, front verticle flanges, in that order)
9. Allow to cure
10. I also posted in Shower/Tub Forum

Thanks in advance,
Keith

 

[Gary Swart]

Keith, I think you are over thinking this. Brand is meaningless. You buy a couple of bags. You do no pour this as a solid bed like a sidewalk, you just put clumps around the area. When you set the shower down, it will squish the clumps out. No, you will not have a solid bed of mortar, but you will have enough to support the shower base.

 

[Sponsor]

 

[Hammerlane]

You do no pour this as a solid bed like a sidewalk, you just put clumps around the area. When you set the shower down, it will squish the clumps out. No, you will not have a solid bed of mortar, but you will have enough to support the shower base.

Exactly how I did mine but I used plaster of paris instead of mortar

 

[Onokai]

I mixed up mortar and dumped it into a plastic bags on my concrete floor so if the shower came out ever it would not stick to floor. I did that also in a few spec homes as well on wood floors.
You just want a firm support in several spots so floor is not spongy. The 4 spots works best.
Mark

 

[kailor]

I really do appreciate all of the replies to the questions I have regarding my task at hand! I guess I should have been more clear on step 2., as I know it won't be a solid pour of bedding material. I just wanted to get an idea of how big/many clumps of bedding material so as not to end up with a ton of the material left over. My ultimate goal regarding this post is to find out what is the best bedding material I should use for my specific application. True mortar or something else (e.g. plaster of Paris).

 

[FMcCracken]

I really do appreciate all of the replies to the questions I have regarding my task at hand! I guess I should have been more clear on step 2., as I know it won't be a solid pour of bedding material. I just wanted to get an idea of how big/many clumps of bedding material so as not to end up with a ton of the material left over. My ultimate goal regarding this post is to find out what is the best bedding material I should use for my specific application. True mortar or something else (e.g. plaster of Paris).

I don't understand why you don't want to use Structolite when you don't seem to have an issue with plaster of paris. Its easy to mix, compresses/ squeezes out easily, but not messy, when you set the pan. Easy. You don't even need a trowel, though it's nice to have one.

I don't use the dollop method. I prefer a full setting bed. It feels better, sounds better when something is dropped onto the shower floor, and there's less risk of a crack developing when there's a full setting bed.

I've been using Structolite for this purpose for 25 years.

 

[kailor]

I've never set a shower stall into any kind of bed before. I've just read and researched till I'm kind of worn out. I really don't have anything against any bed material. I just don't know what to use. That's what I'm trying to get an answer to. I guess the reason I included "(not Structolite)" in my original post was that somewhere I had read that Structolite shrinks or something (convincing reasoning on why not to use it...I guess I totally bought into that idea). Structolite sounds very user-friendly.

 

[Cacher_Chick]

I have used the same mortar we use for setting concrete block with no issues. I set my leveling shims first and tape them in place, then mix the mortar & make some piles so it squishes somewhat uniformly. Set the shower base making sure it bottoms out level, and walk away until the next day.