Return to the Bathrooms Forum | Post a Follow-Up

shower surround questions

Posted by emcloud (My Page) on
Fri, Jun 28, 13 at 11:47

I'm having a tub/shower installed as a replacement to the clawfoot tub in my bathroom. The house is approx. 100 years old.

I realize there are a variety of opinions and previous threads dealing with the subject of vapor barriers surrounding showers, but I'm hoping to get some feedback/confirmation on my specific plan, which is to insulate the shower walls with kraft-faced batts, followed by cement board, then a sealer on the cement board (redgard or something else?), followed by tile.

I don't view the batts as a vapor barrier. They will not be tightly sealed, but will just be stuffed in the cavities with some tears in the paper.

Am I missing anything or is there anything obviously wrong about this plan? Is there anything regarding the type of grout or adhesive that I should be aware of since it will be going on over the redgard?

Also, we're installing a ceiling fan/vent and the shower itself will have a glass block window with a vent in it, so the ventilation should be pretty good.

Follow-Up Postings:

RE: shower surround questions

You can certainly put batts in if you wish, but it serves no purpose other than insulation. Be sure to slice the batts so as to avoid a mold sandwich if you're using Redgard.

RE: shower surround questions

I recommend trying to do a better job.

If you're going to insulate, why not insulate properly? Or at least with a little more effort towards good worksmanship? FG batts are compromised enough when people try to install them correctly, never mind people installing them in a haphazard manner.

A "weak" vapor barrier will allow air to whistle through your stud bays and through your FG batts. Air movement through the batts can drastically reduce their effective R-value, and if that air is carrying warm moisture, in cooler weather the dew point can be reached within the thickness of the batt, resulting in water condensing out within the framing bay and saturating the batt.

It's a bad recipe.

I recommend you use unfaced batts. Let the insulation be just that: insulation.

For the vapor barrier, I recommend 6-mil polyethylene sheet plastic. It's horribly inexpensive. And by being a single continuous unseamed barrier from left to right and from top plate to sole plate, you're creating an effective vapor barrier.

Then install your cement board over the poly'd studs.

Then use a waterproof membrane over the cement board that is not a vapor barrier. Use something like Hydroban (not a VB) instead of RedGard (which is a VB).

If you want to use RedGard and faced FG batts, then do just as StoneTech mentioned. Install your faced (or unfaced) batts. If you install faced batts, slice up the kraft paper with a utility knife.

Then cement board all surfaces of the shower. Detail the seams and corners if needed.

Then RedGard all of the cement board. You should now have a nice water- and vapor-proof shower space. Then tile.

"Is there anything regarding the type of grout or adhesive that I should be aware of since it will be going on over the redgard? "

For tiling over any topical membrane (like RedGard or Hydroban), it's tile as usual. Use a modified thinset. RedGard is a "Custom Brands" product, their modified thinset line would be Versabond which is lightly modified, or Flexbond which is highly modified.

Use a modified grout. Custom's "PolyBlend" grouts are already modified.

Use a dry powdered thinset and a dry powdered grout (which the above mentioned are), each which get water mixed with them to make them usable. Don't use any "premixed" thinsets or premixed grouts that come ready-to-use in a resealable plastic tub. Those plastic tub materials can actually be water soluble. You probably understand using a water soluble thinset in a shower might not be the best idea. ; )

Best of luck with your project.

RE: shower surround questions

Is this an exterior wall you're insulating or an interior wall? I ask because I have an interior wall that I have considered insulating with a product called "ROXUL Safe’n’Sound" to provide sound insulation from the new shower that will share a wall with the living room.

 o Post a Follow-Up

Please Note: Only registered members are able to post messages to this forum.

    If you are a member, please log in.

    If you aren't yet a member, join now!

Return to the Bathrooms Forum

Information about Posting

  • You must be logged in to post a message. Once you are logged in, a posting window will appear at the bottom of the messages. If you are not a member, please register for an account.
  • Please review our Rules of Play before posting.
  • Posting is a two-step process. Once you have composed your message, you will be taken to the preview page. You will then have a chance to review your post, make changes and upload photos.
  • After posting your message, you may need to refresh the forum page in order to see it.
  • Before posting copyrighted material, please read about Copyright and Fair Use.
  • We have a strict no-advertising policy!
  • If you would like to practice posting or uploading photos, please visit our Test forum.
  • If you need assistance, please Contact Us and we will be happy to help.

Learn more about in-text links on this page here