No rainscreen gap in an all-cementitious wall?
ethan_TFGStudio
| Posted in Green Building Techniques on
Some of you who have read my previous posts know that I’m exploring various alternative wall assemblies for a net zero (Living Building Challenge) home. Attached I show a proposed detail of the 1st and 2nd floor walls. I am interested in whether the 1st floor AAC –> Roxul –> Cement Board (w/ stucco finish) is robust without a rain screen gap?
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Replies
Ethan,
You don't need a rainscreen gap on the wall you have described.
Be careful in your cement board product selection- many cement board products aren't rated for exterior use, and can suffer freeze/thaw damage in a zone 5A climate. Fiber-cement siding with a factory applied stucco-like finish is fine, but only above grade.
Rock wool can wick moisture, but the AAC won't (much). what will the interior finish be?
Ethan,
Have you checked on availability for AAC is in your area? I've also read that some manufacturers have reservations about using it below grade.
Thanks everyone...
I am not intending to do any of this below grade.
Regarding AAC availability, I have previously been in contact with Aercon - and got some pricing - though I'm not sure if the hurricanes affected them.
I will look into the appropriate exterior grade cement boards. Do you know of any that are good for exterior use?
My thoughts on interior of AAC would be vapor open stucco/plaster finish with all electrical in conduit.
Martin, would you feel the same way if I were to replace the rigid insulation outboard of the AAC to EPS foam?