Stucco on SIPs
Just interviewed a local reputable contractor to do stucco on my SIP house (99362 zip code). He uses the one-coat system.
He described the preparation before he actually applies the stucco, and I’m troubled by it. If anybody can help me figure this out, I’ll rest better at night!
This contractor attaches two layers of black paper, then one-inch foam, finally the wire. Then he starts the stucco process.
Will this double layer of black paper between the SIP and the foam insulation be enough for the OSB to dry out if needed? Or should I request he uses StuccoWrap instead?
Perhaps this is a non-issue—don’t know, but I thought of checking with you guys before making any decisions. Many thanks!
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Replies
The SIPA (structural insulated panel association) website has some good information on this. They have some info on there regarding fastening (differences from typical wood framing) that you should make sure your installer is aware of. A good question is always "have you done this before?" (specifically SIPs installation).
Robert,
All stucco mfg. must provide with installation instructions and usually you can find them on the internet, or call the manufacturer yourself and have them email you their installations instructions for Walla Walla.
Do not fall into the EIFS Stucco trap of the late 80's and 90's. One coat stucco can be a good product, but you must follow installation instructions and have a great water management plan and details.
If your particular brand of SIPS is using foam for it's center portion, then it sounds like you're running the risk of the dreaded "foam sandwich" If that's the case then neither the felt or the StuccoWrap are going to provide enough ventilation. The application your guy is describing is typical for a conventional frame home with drying to the interior. But in a SIPS assembly, your outer layer of OSB is likely to be oatmeal eventually if it gets pinned between double foam. Seems like you need to think about some 1x furring to create defined air channels. But the bottom line should be with your panel manufacturer. They should have cladding data specific to their assembly process.