Which wall system?
My name is Rob B. I read your article in GBA about Roxul ComfortBoard being used as an exterior home insulation. It was very interesting and is the reason that I am reaching out to you.
In addition to being a Home Performance contractor I am a General Contractor. Currently I am building my personal home. It has been difficult to decide what exterior wall system to use on my home. Arguments are good both ways about using a polyiso board, a polystyrene or an product like Roxul ComfortBoard 80.
Being in the Home Performance business I know that exterior walls are tricky when it comes to “breathing” and being able to “dry” to the interior as well as exterior.
My original plan was to use a Polyiso board for it’s high R value, density, and maybe even it’s radiant benefits in the summer months. But I continue to read info that argues against a non vapor transmitting product like Polyiso or Dow board product.
You indicated in your article that a non vapor transmitting board in this application should not be a concern. I live in Western North Carolina where high humidity and rain are prevalent. Winter temps can get into the single digits but typically not for very long. Summers are hot and humid. I don’t want to run a risk of trapping moisture in my exterior walls. Can you please elaborate on why you think I should not be concerned if I use a polyiso or Dow board product.
I have a poured concrete (10″ thick ) wall foundation with a waterproof peal and stick membrane followed by a 2″ dow product. My walls are 2 x 6 with a Zip wall sheathing system. I will likely dense pack cellulose in my walls between the studs followed by 1/2 drywall. The house will be very well air sealed. Exterior cladding will be stone, stucco and LP composite siding.
Thank you for any input that you may have.
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