insulation between exterior stucco and interior tiled shower

[spallhead]

Should I install unfaced insulation in the wall- exterior face is stucco and interior face is a tiled wall for a shower.

thanks

[James Eggert]

Generally all exterior walls should be insulated in order to limit the coolness of the tile. Should have been insulated as it was built, but any insulation will be better than none!

[spallhead]

Oops, I guess I should have been more detailed in my question.

I'm definitely going to install insulation. Usually, I install faced insulation with the paper facing the conditioned space. In a wall with the building paper/vapor barrier for the stucco on the exterior and the building paper/vapor barrier behind the hardibacker for the shower tile, I'm thinking the insulation should maybe be unfaced, so as not to have two vapor barriers next to each other.

thanks

[kfc510]

In a wall with the building paper/vapor barrier for the stucco on the exterior and the building paper/vapor barrier behind the hardibacker for the shower tile, I'm thinking the insulation should maybe be unfaced, so as not to have two vapor barriers next to each other.

If you're counting both the inside and the outside of the envelope as already having vapor barriers you're already acknowledging a technical problem... but I'd imagine the reality is that in most parts of southern California it really doesn't matter too much.

Heck, we've been putting "encapsulated" insulation
http://www.specjm.com/commercial/ins...capsulated.asp
(with plastic on all four sides) in walls in the bay area for years with no problems. The delta T and humidity just isn't enough to present issues (generally).

(Cue the building science gurus in 3...2...1...)

kevin

[calvert]

Spallhead, if you are using #15 or #30 building felt, neither of these items is really a vapor "barrier". Either product is relatively permeable to vapor in their dry state and extremely vapor permeable in a wet state.

As far as the interior side of the installation goes, Hardie Board should be installed with a vapor barrier if recommended by your local code.

As Kevin has pointed out, your location is very forgiving from the aspect that dewpoints should ever create any long term issues.

AS a sidebar, the JM encapsulated insulation has a permeable "cold side" poly film. The "warm side" facing does function as a technical vapor barrier.

From a technical position, your ceramic tile MAY function as a vapor retarder/barrier, but there are so many possible considerations with regard to that discussion that I don't really want to go there. Suffice it to say that in your climate I believe that you would be safe, from a vapor transmission viewpoint, with whatever you do.

[kfc510]

AS a sidebar, the JM encapsulated insulation has a permeable "cold side" poly film. The "warm side" facing does function as a technical vapor barrier.

I did not know that.
k

[spallhead]

Hmmmm,...okay, so the building paper on both sides of the inside of the wall is not considered to be a vapor barrier, but a moisture drainage system for moisture that permeates either through the stucco or the tile/ grout/ thinset hardibacker or mortar?

Thanks for the responses and feedback. Yeah, it's not too extreme here. Now I'm curious how they do it where they have real weather.


thanks