Mastic versus Thinset

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  #1  
Old 06-15-10, 12:51 PM
Z
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Mastic versus Thinset

I am tiling a bathroom.

For the shower floor, I have a 2x2 tiles set in a 12x12 mat.

For the shower walls, I have 12x12 marble.

For the bathroom floor, i have 12x12 marble.

I bought the Omni-grip from HD since they told me that it would have some "give" and wouldnt crack the large marble. Although my "spidy senses" tingled, I bought and installed it for the floor.

Only the floor is done, i didnt do the rest yet.

Three days later, the floor is still wet, the tiles move if I push them. Do I pull the whole thing up, clean and scrape the mastic off the tiles, scrape the floor and do it again with thin-set. Or do I just let the damn stuff take 2 weeks to dry.

What stuff should I use for the walls? shower walls? what is the best suggestion? I sure as heck dont want to use the mastic.

Thanks!
 
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Old 06-15-10, 02:45 PM
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OmniGrip or any other mastic should never be used on a floor for the exact reasons you have discovered. Mastic should only be used on backsplashes with ceramic tile.

I would start pulling those tiles as soon as you can, clean them off, and use thinset.

Get Versabond or Flexbond from HD. You can use that for the floors and walls.
 
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Old 06-15-10, 08:41 PM
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In addition to what Mark told you;

I will bet you your subfloor system is not rated for natural stone. Natural stone tiles require a floor that is much stiffer than the norm.

Tell us how you've built the shower floor, curb & walls in preparation for tiles. Be very specific starting with the subfloor and work up. Do you have any pics?

Jaz
 

Last edited by the_tow_guy; 07-24-10 at 05:30 AM.
  #4  
Old 07-20-10, 07:13 PM
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Shower floor - cement (sand mix) on top of pvc liner on top of subfloor (wood) ceramic 2x2 laid with thinset.
shower walls - the old walls are perfectly straight and plumb so we left them. it is lathe over wood studs with scratch coat and then 3/4 - 1 inch cement on top of that. Since this is not 100% watertight, I was planning to use the Schluter®-KERDI material applied with thin-set an then the 12x12 marble with thinset on the walls.
curb - 2x4s nailed together with nailgun. then the pvc liner on top of that and then there is a lathe and then cement board (no nails on water side of liner)
floor- the bathroom of rest of floor is standard subfloor and then cement board. 12x12 marble will be set with thinset now.

Thanks,
/Z
 
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Old 07-20-10, 09:06 PM
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Im sure the pros will chime in with more insight, but i would also use the kerdi on the shower floor. They actually sell the whole kit with pan, curb, drain, and all the membrane to do a 4 by 4 shower. Costs about 600 bux.
 
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Old 07-21-10, 05:05 AM
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Do you have a preslope mud layer UNDER your liner as required?
 
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Old 07-21-10, 08:29 AM
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The schluter kerdi system isnt really made to mix and match. Either do a whole kerdi shower or don't use kerdi. If you decide to build a conventional shower, check out this link to build a proper shower pan.

Building a shower pan with pre-sloped mortar bed, liner and curb.

As Mark said, don't forget to install a preslope under the pan liner. The shower pan will eventually fail without a preslope.

Your best bet here would be to go to the Schluter website and check out the kerdi showers. Theres a ton of real good info their. Kerdi showers are 100% waterproof if constructed properly. In addition, only one mud bed is required. You'll spend a little money on materials, but the install will be easier and you'll have a water tight shower.
 
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Old 07-21-10, 05:34 PM
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Z,

You do not have a pre-slope under the membrane and so that is wrong. I am also wondering how you installed the membrane on the floor and up the walls with the old mud walls still in place.

Also how do you install cement board without fasters. Also what is the lath for if you used cement board.

It sounds like there's several faults in the construction of your shower.

Also the bathroom floor needs a double layer subfloor and probably the joists should be stiffened.

Jaz
 
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Old 07-23-10, 06:15 AM
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Maybe I read this wrong. Z have you already done the shower or are you just asking questions first?
 
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Old 07-23-10, 07:01 AM
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What has been done already?

We know Z did the bathroom floor with the bubble gum junk. I thought the shower was started too since in post # 4 he said...the old walls are perfectly straight and plumb so we left them. Maybe not.

Jaz
 
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Old 07-23-10, 07:11 AM
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Mastic/Pitch and walls

Lots of responses. Thank you.

To reply. we got most of it somewhat right

For the walls, we actually ripped out bottom 18 inches of walls to the studs, attached the liner to the studs and used furring strips to align new cement board to walls.

regarding the pan, the wood was pitched already. i guess years of weight. i presloped mud would have been better. how many years will a shower last without a presloped mud floor. assume the grout on the floor is tight, strong and sealed yearly. I am amazed that this passes inspection without the presloped mud floor.

The bathroom isnt tiled yet except for the shower floor. I asked a contractor to come in and review it.

/Z
 
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Old 07-23-10, 09:16 AM
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So, it's the shower floor that is set with OmniGrip? Why wasn't that removed yet?

Then wood subfloor was pitched already.......how is that possible?

How in the curb built?

Jaz
 
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Old 07-23-10, 11:18 AM
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shower floor

no. Omni-grip sucks!

I ripped up the entire damn floor, returned the omni-crap to HD and then called the manufacturer Custom Building Products and railed at them for a crappy product.

Then i re-did the shower floor with Versabond thinset.

I am waiting for more tiles. No other tiling is completed.

the curb has liner over it. then I wrapped metal over it and put screws on outside of curb to hold the metal in place. I will be building up the curb and tiling.

/Z
 
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Old 07-23-10, 01:41 PM
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Is the lath over the curb also running under the shower floor mud? It doesn't sound to me that it is. Normally you would mud the shower floor and also the curb at the same time. (Using a different type of mix of course). If not, what's gonna hold the curb mortar in place since the lath is not part of the deck mud?

You also stated you removed the lower part of the walls, installed the membrane, then shimmed and installed a cement board. What are your plans to waterproof that?

Jaz
 
  #15  
Old 07-25-10, 09:57 PM
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lathe

curb was dont at same time and lathe is in mud. plans where to use the schluter stuff on the walls.
/Z
 
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