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Durock Seams..modifed Thinset or 'unmodified'?

Posted by aaron2005 (My Page) on
Wed, Dec 12, 07 at 9:12

I know from this thread:

http://ths.gardenweb.com/forums/load/bath/msg0715344223217.html

to use thinset on the Durock Seams, and Durbond between the durock & green board...

Does it matter to use modified thinset?

Cheers,
Aaron

Here is a link that might be useful:


Follow-Up Postings:

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RE: Durock Seams..modifed Thinset or 'unmodified'?

For Durock seams use a modified thinset. Modified used to be called for by USG, I don't think their specs have changed.

Mongo


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RE: Durock Seams..modifed Thinset or 'unmodified'?

The very same thinset you're setting the tile with. Both should be done at the same time, anyway, so that you don't end up with "speed bumps" in the wall.


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RE: Durock Seams..modifed Thinset or 'unmodified'?

The only issue there is that I am planning on using RedGuard waterproof membrane.

If I can use mesh tape, redgaurd, and then when the tiles goes on apply the thinset then, I'll do it that way.

But I thought that since I am using Red Guard, I need to do the seams 1st, using mesh tape & thinset..and then apply Red Guard...and then when the tile goes down, a new layer of thin set will go down.

However, this is a spare guest bathroom..and part of me is thinking maybe to put a water vapor barrier behind the durock INSTEAD of putting Redgurad on TOP of the Durock. Then I don't have to worry about the "spead bumps"

This bath is a standard 30"x60"x14" tub, with Durock on 3 sides. What do you guys think? JUst use the vapor barrier..the red guard is overkill? Or do the Red Guard?

Thoughts?


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RE: Durock Seams..modifed Thinset or 'unmodified'?

But I thought that since I am using Red Guard, I need to do the seams 1st, using mesh tape & thinset..and then apply Red Guard...and then when the tile goes down, a new layer of thin set will go down.

Yup-- yer right. :-)

JUst use the vapor barrier..the red guard is overkill? Or do the Red Guard?

let me put it this way-- waterproofing vs a vapor barrier is ALWAYS better. But it's also not really necessary, if you don't want to put the money into it. It's not like it'll increase the value of the home, although it will help in making that shower last longer.


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RE: Durock Seams..modifed Thinset or 'unmodified'?

Hummm....I understand what you are saying, I am just wondering which direction to fall :).

The vapor barrier sounds like it is sufficient to do the job, and is the easiest in terms of putting it up...then Durock..and then the seams will be done when the tile gets done...very simple; and should work fine.

The Red Guard route sounds like the "best" route in terms of water protection, however it does add some complexity (obviously), but only in terms of the number of steps needed.

If I use 6mm thick vapor barrier, I should be fine..or I can go the extra steps of using Red Guard...man, I hate making decisions ;)

Thanks for the info,
Aaron


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RE: Durock Seams..modifed Thinset or 'unmodified'?

Just as an FYI, I am going with the Vapor Barrier route. I thought about, and the extra stuff I would have to do with Red Guard, I talked to my friend who builds houses, and he says what Bill says..Red Gurad is the best, but I should be fine with Vapor Barrier. He came by last night and we talked about some things to watch out for (we have a Window in the tub area), and make sure that the barrier goes over the lips of the window, and work like you were working on a roof, etc, etc.

Thanks for all the help
Aaron


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RE: Durock Seams..modifed Thinset or 'unmodified'?

"A" window? Piece of cake! I just durocked a bathroom I'll be tiling in about 2-3 weeks-- all 1" hex tile, 10' high walls, ceiling, and floor-- this is the SHOWER:

Photo Sharing and Video Hosting at Photobucket


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RE: Durock Seams..modifed Thinset or 'unmodified'?

Nice...I haven't got it that bad, but I just need to make sure the ledge of the top window has the vapor barrier "roll over" it. Same thing with the bottom ledge.


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RE: Durock Seams..modifed Thinset or 'unmodified'?

Is it wood frame like the ones above, or is it vinyl wrapped?


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RE: Durock Seams..modifed Thinset or 'unmodified'?

Wood.

I am going to put an oil based primer, a couple of coats.

Then for the top, make sure the vapor barrier goes over the edge and down about 1/4-1/2" (the tile will cover it). And for the bottom, put vapor barrier that comes over the inside part of the sil and down under the bottom of the lip..but, ontop of the lower part of the vapor barrier..kinda like a roof.

At each long corner, put a bead of construction adhesive so that the vapor barrier "sticks". I know I will need a bunch of play.

Here are a couple of Pictures.

I need to sand down the entire edge, I know.


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RE: Durock Seams..modifed Thinset or 'unmodified'?

Look into a paint called "Interlux". it's actually a boat paint, but made for waterproofing wood. I've already worked on a couple of projects where it was used, one of them being this steam shower:

Photo Sharing and Video Hosting at Photobucket

(oh yeah-- that orange membrane on the wall is Kerdi. :-) )


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RE: Durock Seams..modifed Thinset or 'unmodified'?

The Durock seams should be thinset and "taped" with the special mesh..correct?

And the Kerdi...everyone is trying to convince me to use greenboard for ease of installation? Is this OK.

And the HD guys is trying to convince me to use a new Custom product that is light as a feather and feels like foam. How can this be used for a wall. Won't the wall flex?


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RE: Durock Seams..modifed Thinset or 'unmodified'?

I am putting in Durock. My friend also told me to take the extra 15mins, and put a blocking row of flat 2x4s between the studs on the top & bottom, so the Durock can be secure to those as well. It helps with stability because the Durock is about 1/2" above the tub...basically right at the lip. The reason you do put the Durock right there is to prevent water going up the Durock IF for some reason the calk goes bad.

So, he recommended putting 2x4s in even with the lip of the tub, and flush with the studs to help with stability. He did say it is a little overkill, but, if you have the time (which I do, spend the extra $3 and do it). For the top row of 2x4 blocking, since Durock is 3'x5', they will be at 3' above the tub.

From what I have read, use a modified thinset as the "joint" compound, and yes you need to use a speical mesh tape.

As for greenboard under Kerdi..don't know. Haven't heard of the HD stuff..but IMHO, I would stick with what Bill says to do.


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RE: Durock Seams..modifed Thinset or 'unmodified'?

Re the greenboard, let me put it this way-- Schluter says it's okay to use kerdi over greenboard. I don't trust it for longevity sake. I'm not so much worried about water penetrating the membrane as I am about condensation forming on the back of the membrane causing the greenboard to rot over time. For the little bit of extra cost involved, I won't chance it on my jobs. As for the Custom product, I'd be curious what they're pushing. What you're talking about sounds alot like Wedi board, which I don't care for, but that's not a Custom Product, and I just checked Custom's site. The only backerboard that Custom has is Wonderboard, which is no where NEAR light as a feather!! Unless you're talking about a membrane called Easymat, which is more of a floor sound proofing membrane.


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RE: Durock Seams..modifed Thinset or 'unmodified'?

Custom has Easyboard in 1/4" and 1/2"

It is very light, scary light. I would really like to know how this stuff works. The HD guy in a demo cut it easier than sheetrock.

I would not be comfortable using unless it has been tried and tested.

Here is a link that might be useful: Easy Board


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