An inspection of a 1940s house turned up a layer of what looks like wood fiber insulation under the more recently blown in insulation. I tried a couple searches on the web, but nothing real close. The insulation is dark brown and almost looks like the stringy wood mulch you use in landscaping. Can any of you gurus help the FNG here and let me know what type of insulation this is and if there are any concerns?
Many thanks…
Bryan,
Do you have a picture?
How did you notice it if it was installed under the blown insulation?
Could be Silva Wool. I have seen it in many older homes, and have not heard of any major concerns as of yet. Hope this helps.
The description of Silva Wool seems to fit - thanks much…
Sorry, I did not get a picture - the house had enough issues that my camera was running low on power so I was prioritizing pictures 
It was visible right at the crawlspace entrance where the blow-in did not cover. At first I thought is was animal nesting, but found it to be uniform as I pushed back some of the blown-in…
Thanks again…