Wire Mesh in Shower Pre-pan?

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mnRemodeler

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I'm building a shower. I had to remove sections of sub-floor to add the roughed in plumbing.

The original sub-floor had 3/4" OSB with a 1/2" OSB on top of it. Glued and Screwed. Sitting on over-sized TJ trusses.

I added another 1/2 layer of OSB over the above sub-floor in the area of the shower. So my shower has 1 3/4 inches of OSB. Plenty rigid. Also, adding that extra 1/2 inch gave me a solid sheet of OSB that spanned all the joints on the bottom layers of OSB that were there after the rough-in plumbing.

I then put down tar paper and floated a pre-pan using floormix made for that purpose and at a 1" depth at the perimeter and a 1/4" depth at the drain. That gave me a 1/4" per foot slope to the drain.

After doing the above, I'm now seeing videos where they recommended putting down wire mesh over the tar paper before floating the pre-pan. I didn't use any mesh because the tile shop's video, which I was using as a guide, didn't suggest wire mesh.

But based on my experiencing doing concrete floors, I know that mesh laying flat on the ground doesn't do anything. This would be the case of the shower pan since no mortar would be under the mesh.

So my question is...how critical is this wire mesh? I assume it helps prevent cracking, but again, without it being embedded in the mortar I'm skeptical that it would provide any value at all.

I'm not inclined to rip it out and add the mesh. I'm just curios how many people use the mesh and if anyone has seen a problem not using the mesh.
 
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ShowerDude

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by mesh you mean lath?

how did you conclude 1/4" of crete at drain flange is sufficient? and what floor mix was it you used? TCC ?

the lath gives mortar purchase to substrate, you have essentially skmmed a floating floor at to thin a thickness likely, w zero purchase.

the felt paper stops the water from wicking the lath if installed properly holds it down.

regardless your trifecta of subfloor its not the way to go...
 
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mnRemodeler

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by mesh you mean lath?

how did you conclude 1/4" of crete at drain flange is sufficient? and what floor mix was it you used? TCC ?

the lath gives mortar purchase to substrate, you have essentially skmmed a floating floor at to thin a thickness likely, w zero purchase.

the felt paper stops the water from wicking the lath if installed properly holds it down.

regardless your trifecta of subfloor its not the way to go...

Yes wire mesh and lath are synonymous around here, This is a pre-pan not the actual shower pan. Its only purpose is to establish a 1/4" per foot slope. Then the liner goes down, then the actual mortar shower pan goes down. The 1/4" at the drain matches the height of the drain. That's pretty standard. The mortar has to be flush with the drain so that when you install the liner its flush with the drain.

The OSB sub-floor is perfectly fine. You don't need durarock or anything else as long as your floor is rigid which mine is at 1 3/4 inches thickness.
 

ShowerDude

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im sorry are you angry?

were you asking for confirmation on how to do it wrong?

or telling us all something?

share with us how youve bonded your preslope?

and again the concrete mfg specs that ok,s the "mystery" mix you used at an unbonded thick ness of 1/4"

was trying to belp, but go ahead carry on share some more of your methods and enlighten us when you do rip it out from
a cracked shower pan...
 
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Vegas_sparky

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The best part of DIY is the fact you have no one to blame but yourself when it doesn't work out right.

The 1/4" material at the drain is not thick enough by all the installation standards I've read about.

Hey Erik, I run with scissors! Take that! :D
 

ShowerDude

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Vegas I would run from your scissors with my trowel. im pretty fast.

HJ stirrin up the pot...Love it.

WOW.....John and Roberto leaving Jim in the dust has left a big gaping hole here on the shower forum...Seems posts have dropped here. ? wonder why
 

Jadnashua

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Some deck mud suppliers specify at least 1.5" minimum thickness with their product. The TCNA allows a little less when used over a wooden subfloor (i.e., a floating one - if you were bonding it to a slab, that's a different story). 1/4" at the drain over a wooden subfloor is just asking for it to break up, even with a fortified mudbed material. TCNA calls for lath in the preslope over a wooden subfloor. Using one of their approved methods is reliable. Choosing to ignore it is pretty risky. It's your house, but don't say you weren't warned when it fails down the road. You have the same minimum thickness for your setting bed when using a conventional liner.
 

Vegas_sparky

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Vegas I would run from your scissors with my trowel. im pretty fast.
You best run!Your trowel is no match for my scissors (unless I have dead batteries, then I'm toast)!

1385498938527.jpg


Last I heard John had installed some modded thinset on top of some orange stuff. There was a bright flash, and this is all that's left. :D

diy-concrete-zombie-hands-3.jpg


I don't believe it myself, but unless we hear from the man himself, its orange stuff=1, and Wonder Whipple=0.

Has he been defeated? Can it be true? Is he stuck between interlocking, dovetailed trapezoids of death, and can't get out ? Will Roberto extracate him with his Super Angle Grinder powers of perfection?

Only time will tell. I keep tuning in. :D
 

Eurob

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Jadnashua

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If you had a choice of forums to get tiling advice from, would you choose one where Mapei, Noble, Laticrete, and other manufacturers monitor and offer advice along with a group of hundreds of professional tile installers, or one more primarily focused on plumbing? That forum is www.johnbridge.com. They do not allow insults, character assignation's, or other attacks on members who are trying to help and will remove posts and members that practice that (FWIW, John Whipple is not welcomed there). They offer a separate forum for pros to discuss workplace issues and new materials, and one more dedicated to helping DIY'ers handle their (maybe first) adventure into things being tiled. Throw in lots of references in their library to industry standards and suggestions, it is much more organized for someone just entering the world of tile. One thing I've said many times is there's a place for workplace discussions and another for people that may never have done anything related to tiling before. Lots of little subtleties you only learn by doing or being shown. The methods espoused as being the only way to do something by some just may not work for a first-timer who doesn't understand the consequences of straying from industry guidelines.

I fully trust the plumbing pros on this site to handle issues like how best to deal with the drains, supplies, and choices of hardware to build up the infrastructure for things like a shower or other bathroom or kitchen plumbing projects that may include a shower or tub installation, but not necessarily on how to best waterproof or construct their shower. And, we have some very talented pros in the electrical and HVAC areas. Members in the tiling area that flaunt or totally dismiss industry standards or manufacturers' instructions without justification other than their unfounded beliefs should not post, or if they do, should be moderated (but, that takes someone who has a deep knowledge and is unbiased...something that does not exist in this area of the forum).
 

Vegas_sparky

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The beliefs you speak of are founded in experience. That is something you personally lack. Reading, and the controlled environment of a manufacturers workshop are NO substitute for dealing with field conditions which change on every project. Working through those projects, figuring out solutions to uncommon circumstances, and having to pay out of your own pocket if things go wrong, are invaluable experiences that can't always be learned, except by doing.

You can reply, parrott installation standards, and play master of the universe, but I've never seen a picture of ANYTHING you've ever done. It's all horseshit, AFAIC.
 

Vegas_sparky

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Me personally, I appreciate what Erik, Roberto, and John share here because they're willing to think outside the box, innovate, and push their own boundaries. They do it with serious thought, not reckless abandon. It may be past the technical expertise of a typical DIYer, but it provides loads of inspiration if you're paying attention.
 
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