How does wall insulation work, and will cellulose insulation mold?
I am in the design phase of a small house approx 800 s/f, and have been planning on using 2x8" walls with staggered 2x4" studs. For insulation I am planning on wet blown in cellulose. I will have osb on the exterior, with Tyvek or some other vapor/moisture barrier and drywall/sheetrock on the interior, with no rigid foam. These walls should be pretty close to R-30,. In the attic, loose blown in to around R 40 to 50. I live in N. Colorado in zone 5B, and although we barely know what humidity is, winter temps can be -20F and summer temps +100F. This is not a passive house, but it will be fairly air tight in the winter, windows cracked weather permitting.
I started to worry about the walls after attending a talk about Net Zero houses put on by a local energy group, NCRES, and the speaker was from a SIPs manufacturing company. He said anything other than foam will rot. He was clearly biased toward SIPs, but it made me wonder, about dew points and how a wall actually works. We are making walls less and less breathable and cellulose is an organic material...
It is probably best to talk about the houses ventilation system in another thread, but we are thinking a ductless mini split, to supplemental heat and some trickle vents, with no HRV or ERV. We want inexpensive, mostly natural, and low tech solutions whenever possible.
Posted May 8, 2014 3:18 PM ET
Edited May 12, 2014 6:28 AM ET
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