Insulation, Radiant and Vapor Barriers - old f/g batt insulation damaged/ disturbed

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brinainlakeelmo
03-24-08, 07:57 AM
Hello
I would like for someone to explain the importance of the vapor barrier to me. The reason I ask is that the insulation (f/g batts) in the attic of my 1966 Minnesota rambler is in rough shape. The previous owner, who lived here from 1966 thru last year when my wife and I bought this fixer upper, shared this space with heards of mice. The home inspector told us that there was "evidence of lots of prior rodent activity" in the attic. Well he wasn't a kidding! We gutted out the kitchen and found pounds of rodent remains, even the skeleton of an albino squirrel. There was no smell to any of it, and we haven't seen any evidence of activity since we moved in - I installed new seals and weatherstripping around the house right away, and of course we do have a cat. I set traps in the attic and none have been disturbed. Last summer, we removed/ replaced all of the insulation in that kitchen, installing fresh poly and f/g batts before sheetrocking. Since, I've been replacing dated can lights throughout the main level and have seen that the insulation throughout the attic is quite disturbed, ie: shreded and filled with birdseed, mouse feces and urine.
Also, there are several places where the insulation and its paper vapor barrier are completely gone, presumably chewed up and used for nesting.
Any tips/ advice would be appreciated
Brian


resercon
03-24-08, 11:18 PM
http://www.eere.energy.gov/consumer/your_home/insulation_airsealing/index.cfm/mytopic=11810

This site will give you some insights on vapor barriers. Considering the age of the house, the several layers of paint on the ceiling would qualify as a vapor barrier.

The purpose of vapor barriers is to prohibit condensation as an object reaches "Dew Point". In other words, vapor barriers retard the movement of moisture going through them. So even if the object reaches "Dew Point Temperature" there is insufficient moisture in the object for condensation to occur.

brinainlakeelmo
03-25-08, 08:06 AM
Thanks Resercon for the reply and link - I will check it out.
I kind of wondered if paint could serve the same purpose as effectively of more effectively than the paperbacked insulation. I don't see how the paper, even if installed correctly and not disturbed could work well, unless all the seems were taped.
Brian