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Do pre-fab fiberglass shower stalls get set in mortar?

Do pre-fab fiberglass shower stalls get set in mortar?


  #1  
Old 03-06-15, 07:11 AM
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Do pre-fab fiberglass shower stalls get set in mortar?

Some of the better-built stalls have a thick plywood plate under the stall floor that's overlayed with fiberglass. When I step inside the floor doesn't flex. 20+ years ago I installed a 3x3 stall like that and didn't set the base on or in anything other than the floor. Did I do it right?
 
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Old 03-06-15, 07:25 AM
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If it's not cracking or flexing then it was right.
How any tub or pan is installed totally depends on the manufacturer and there instructions.
Some are self supporting, others use mortar or even have a built in foam support.
 
  #3  
Old 03-06-15, 07:35 AM
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My 3' Kohler shower stall was not supported and after about 15 years it developed a crack across the bottom. The 5' replacement is currently waiting for my project to get going again, in warmer weather, but it does specify that it should be set in mortar. Concerned about just how I could do that (by myself) and what the real purpose was, since the base unit has lots of supporting feet there to keep it from flexing, I went searching. The mfg web site said I could use simply a pad, but the blue box never heard of that and of course didn't have "the recommended pad". More searching, and the conclusion I came up with was a pad or something was needed to keep it, are you ready, from squeaking.

Having my old Kohler crack, IMO, some form of support should be added unless the mfg specifically says not needed.

One of the drawback to a larger shower stall is that two people can get in there at once. Although that was reminiscent of the huge walk-in shower we enjoyed on our (long ago) honeymoon in St Thomas, it probably wasn't the best practice for the life of the shower.

Bud
 
  #4  
Old 03-06-15, 12:03 PM
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I bought mine at a plumbing supply "tent sale" of sorts. New but without the box or any instructions--if it ever had any.
I bought an identical one used for my cottage that I hope to install later this year.

I was wondering if some large dabs of low-expansion (window & door) foam might be better than cement, or could be sprayed in place before the drain fitting is installed. In an "alcove" installation this would be easier than trying to remove excess mortar squeeze-out.
 
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Old 03-11-15, 06:22 PM
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Does anyone have any tips on doing this. The instructions with my shower only indicate that mortar supports should be used. Then it shows what appears to be two globs of mortar supporting the center around the drain? This unit also has adjustable feet that are obviously not meant to be set in modar. Any help or suggestions would be greatly appreciated.
 
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Old 03-12-15, 03:32 AM
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Rufunky, do you have a link to your installation instructions? Otherwise we are only guessing for your particular model.
 
  #7  
Old 03-12-15, 07:53 AM
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Hi, czizzi. The product is Maax tigris it can be found in the link below along with the users pdf. I also attached a picture of the bottom of the pan to show it's iregular shape. Therfore making it hard to build a support. I thought about using expanding foam while the unit is on it's back and leveling it to the feet so I have an even surface to work with.

I also left out what could be an important detail! The unit will have to be raised for p trap clearance of the concrete slab below. It is being connected to a saniflo upflush system.I planed on just building a PT frame under the feet until I reach the desired height and using a flex base molding to fill the gap between the base and the floor.

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Tigris Round Corner shower - MAAX
 
  #8  
Old 03-13-15, 06:22 AM
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The instructions show two heaps, but in reality, it would be a ring of mortar around the drain with a hole in the middle (like a donut). It would be around 3" thick or so, which is too thick for thinset. I would use a bedding type mortar that is mixed really dry and you can shape it with your hand. Make it slightly thicker than is needed. Set the base and add some body weight until it settles down and the feet touch and then leave overnight. Bed mortar usually has felt paper and wire mesh under it to give it something to grab and to prevent the wood from pulling too much water out of the mix. Then again, I usually use bed mortar to make custom shower floors.

Of bigger concern is the size of the step needed to get a 2" trap above grade. Plan on a step up and a landing then your shower. It will be easier to get in and out of and easier to trim out.
 
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Old 03-13-15, 04:36 PM
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Thanks for the detailed explanation. I guess I wasn't familiar with bedding mortar. The only stuf I have any experience with is thin, pourable, set over night type. As far as the step up, I was hoping to keep it to the height of a stair riser ( around 7" ) Honestly I have been going back and forth on just breaking concrete and putting in a proper sewage pit. It's too bad I already spent $1,200 on the saniflo, toilet, alarm and extender pipe :/.
 
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Old 03-13-15, 05:45 PM
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NIBCO 2 in. PVC DWV Hub x Hub P-Trap-C4885HD2 - The Home Depot
According to the specs on a 2" solvent weld trap for your shower, the dimensions are 7 inches high and 9 inches wide. Minimum 2x8 to just squeak by which is 7 1/4" plus 3/4" decking material puts you at 8 inches. Big step up to go directly into a shower. Then factor at what height the saniflo inlet is and make your adjustments. That is why I mentioned a landing in front of your shower to accommodate the large step up. You could have rented a large jack hammer, brought in a load of concrete and done a whole lot to make it right for the $1200 spent on the up flush system.
 
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Old 03-13-15, 06:18 PM
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(A bit O/T but just curious) I have installed a couple that had instructions that said to use premixed drywall compound. I wonder if that was an oddity of the manufacturer. Looking back now I really question those instructions because drywall compound cracks when it is too thick. Anyone seen instructions like that? Doing a a quick search I see that method mentioned but another site saying using drywall compound voids the warranty. Personally mortar I think makes a lot more sense
 
  #12  
Old 03-13-15, 06:44 PM
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I think that setting type compound would be better as it is not subject to cracks from drying due to evaporation. It drys by a chemical reaction. However, the problem is that the instructions are so vague that you really don't know what to use. A 3" void is a whole lot different than a 3/8" void. Most thinsets are not rated for the thick set as in this situation. You there for have to move up to a thick set type of material. Thinset says thin for a reason.
 
 

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