Insulation – Insulsafe vs sheep wool blankets
We are building a passive house, but won’t be certifying. Primarily we would like to enjoy the health benefits.
We are getting quotes on insulation. Our green build advisor suggested Insulsafe SP. I want to compare that with sheep wool blankets. As that’s what I had in mind from the beginning.
I’m actually open to using wool for the most part, and blow in fiberglass/Insulsafe SP stuff into nooks and crannies. Since it’s hard for blankets to reach everywhere. (blowing in sheep wool sounds like it will cost me an arm and an leg).
We live in Seattle, so moisture wicking is on my mind.
Question is, how safe and how healthy is Insulsafe SP. I can’t that much info on google.
Much appreciated. Thank you.
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Replies
All insulation types can work. There is no magical safe insulation, what is more important is the envelope details (air barrier, water barrier, moisture management) and the quality of the insulation install.
Pretty much any fluffy insulation that doesn't use a formaldehyde binder is "healthy".
I would be a bit worried about sheep wool as some people are allergic to it. It would be hard to install the sheep wool blankets in walls, the installer would have a very hard time installing it without gaps (you want Grade I, which is a must for good R value) , should be fine for attic floor though.
Generally the green and "healthy" insulation is borate treated cellulose. Works great dense packed in walls and as a loose fill in attics.
What Akos said: Dense packed cellulose in walls using a product with only borate fire retardents would be greener, cheaper, and less problematic than wool, and use open blown/loose in attics too. For relative verditude (on a carbon basis) see:
https://materialspalette.org/wp-content/uploads/2018/08/CSMP-Insulation_090919-01.png
In Seattle the most important feature for mitgating against exterior moisture wicking into the walls is the providing a rainscreen structure to the cladding, with a vented air gap between any sheathing and siding. Even 1/4" of air is a GREAT capillary break. In Vancouver and most of western B.C. a minimum of 10mm or 3/8" rainscreen is now required by code, but not on the WA sided of the border. That would be a far more significant improvement to the moisture handling characteristics of your walls than than wool vs. fiberglass. vs. cellulose.