roll on waterproof membrane- any experince?
#19
  Re: roll on waterproof membrane- any experince? by tomsteve (im getting ready to ...)
What I read (and am planning to do) is that cement board is not waterproof but does not expand when it gets wet.  

It is therefor necessary to staple 6 mill poly sheeting on the studs to keep them dry.  

Any waterproofing beyond that is optional and I was planning on rolling on the red film.

I am not sure why they say you should leave a small gap between panels.  I found no explanation for that.
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#20
  Re: RE: roll on waterproof membrane- any experince? by Cooler (What I read (and am ...)
(02-05-2018, 10:12 AM)Cooler Wrote: What I read (and am planning to do) is that cement board is not waterproof but does not expand when it gets wet.  

It is therefor necessary to staple 6 mill poly sheeting on the studs to keep them dry.  

Any waterproofing beyond that is optional and I was planning on rolling on the red film.

I am not sure why they say you should leave a small gap between panels.  I found no explanation for that.
 You are sandwiching the cement board between two vapor barriers,  this is not recommended as mold will form if any moisture is between them.   If you want something on the stud side use a item like Tyvek ,  it waterproofs but allows vapor to pass.    If you apply the Red Guard as instructed you will see it will not leak.    Make sure you tape the joints with thinset and thinset the screws.   Roly
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#21
  Re: RE: roll on waterproof membrane- any experince? by Roly ([quote='Cooler' pid=...)
(02-05-2018, 06:01 PM)Roly Wrote:  You are sandwiching the cement board between two vapor barriers,  this is not recommended as mold will form if any moisture is between them.   If you want something on the stud side use a item like Tyvek ,  it waterproofs but allows vapor to pass.    If you apply the Red Guard as instructed you will see it will not leak.    Make sure you tape the joints with thinset and thinset the screws.   Roly
They said to use special alkali-resistant fiberglass tape or the thinset will destroy it.  Any truth in that?
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#22
  Re: roll on waterproof membrane- any experince? by tomsteve (im getting ready to ...)
Just remember if you're going to use the fabric membrane then you have to use the unmodified thinset to adhere it and also to install the tile on it. For redguard you have to use the modified thinset.
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#23
  Re: RE: roll on waterproof membrane- any experince? by Cooler (What I read (and am ...)
(02-05-2018, 10:12 AM)Cooler Wrote: What I read (and am planning to do) is that cement board is not waterproof but does not expand when it gets wet.  

1) It is therefor necessary to staple 6 mill poly sheeting on the studs to keep them dry.  

Any waterproofing beyond that is optional and I was planning on rolling on the red film.

2) I am not sure why they say you should leave a small gap between panels.  I found no explanation for that.

1) Highly debated. Poly also traps any moisture and you'll get a mold problem if the shower ever does leak. I've done it both ways. In my opinion, if the cement board is properly installed, corners properly done (thinset and mesh tape and several coats of painted on membrane), properly framed and a good quality barrier like RedGuard or AquaDefense it won't leak.

2) You do this for the same reason you do it installing sheetrock. To gain strength at the seams. The mud (in this case, thinset) flows between the two sheets "locking" them together. Some go as far as installing framing behind all wallboard seams in a shower to prevent any movement at the joints. I use cedar shims between the DuRock panels at about 3/32 in and screw the panels in place, then pull out the shims. Trowel the thinset into the gap and mesh tape over it. I leave a little more than that in the corners except in the niches. I trowel the tape into the thinset and smooth it. I don't add a layer of thinset on top of the tape except for smoothing out the excess thinset that pushes out through the mesh. I roll on my sealer on top of that. That way, I don't have high spots to deal with when installing the thinset and tile. The thinset and tile will bed down and cover the mesh tape.
Neil Summers Home Inspections


When it comes to 'lectricity, I'm a pretty good wood turner.

... Grey Mountain 3/2/21

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#24
  Re: RE: roll on waterproof membrane- any experince? by Cooler ([quote='Roly' pid='7...)
(02-06-2018, 08:33 AM)Cooler Wrote: They said to use special alkali-resistant fiberglass tape or the thinset will destroy it.  Any truth in that?

Yes. Use the mesh designed for tile work.

Also, make sure you use the right screws for the panels. DuRock and Wonderboard require different screws. Personally, I can't stand Wonderboard. I think it's hard to work with and the screws don't countersink well and tend to stay proud of the wallboard. I like the rough surface of the DuRock for adhesion reasons and it counter sinks better and it scores and snaps easier. I't a little messy but I can deal with that..

Also, top off your screws with a little thinset, troweled smooth with the surface of the wallboard and make sure they get extra RedGuard/AquaDefense.

I brush VERY LIBERALLY all interior and exterior corners and niches and screws with two or three coats of the sealer and then roll a couple coats of sealer on the entire shower.
Neil Summers Home Inspections


When it comes to 'lectricity, I'm a pretty good wood turner.

... Grey Mountain 3/2/21

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#25
  Re: RE: roll on waterproof membrane- any experince? by Snipe Hunter ([quote='Cooler' pid=...)
(02-06-2018, 09:22 AM)Snipe Hunter Wrote: Yes. Use the mesh designed for tile work.

Also, make sure you use the right screws for the panels. DuRock and Wonderboard require different screws. Personally, I can't stand Wonderboard. I think it's hard to work with and the screws don't countersink well and tend to stay proud of the wallboard. I like the rough surface of the DuRock for adhesion reasons and it counter sinks better and it scores and snaps easier. I't a little messy but I can deal with that..

Also, top off your screws with a little thinset, troweled smooth with the surface of the wallboard and make sure they get extra RedGuard/AquaDefense.

I brush VERY LIBERALLY all interior and exterior corners and niches and screws with two or three coats of the sealer and then roll a couple coats of sealer on the entire shower.

I second all Neil said.    Remember the special screws,  not drywall screws.   Roly
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#26
  Re: roll on waterproof membrane- any experince? by tomsteve (im getting ready to ...)
Instead of hijacking this thread. I posted a lot of pics in the Shower Install thread. Home it helps illustrate some things talked about here. I didn't uses the Kerdi products because of our budget. We're redoing an entire house out of pocket so we can't do the most expensive work everywhere. Showers have been being built for hundreds of years. They don't leak unless they were built incorrectly. Kerdi is great stuff but it's out of my price range and I don't mind getting my hands dirty if it saves me money.
Neil Summers Home Inspections


When it comes to 'lectricity, I'm a pretty good wood turner.

... Grey Mountain 3/2/21

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