- Jan 22, 2011
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Last summer I bought an 1000 sq ft colonial that was built in the 1920's.
It has about 2 inches of old fiberglass bats covering the attic floor. It has no soffit vents but there are three roof vents.
The roof was constructed using rough cut 2x4 rafters instead of the more typical 2x6 construction:
Also, the roof line actually comes down into the second floor living space:
This creates a cavity about 4 feet long and 4 inches high from the edge of the attic floor to the eave:
This winter was particularly severe and there was lots of ice damming around the roof.
An insulation contractor came over last week and gave an estimate on improving the insulation in the attic. He recommended completely filling in the cavity with either spray foam or dense packed cellulose and blowing in cellulose in the rest of the open attic space. He said that because of the way the roof is constructed, there isn't a lot of room to work with, and it isn't worth adding soffit vents. He also said that there will always be some ice damming no matter what is done, but filling the cavities would cut down on it a lot.
I'm worried about mold and rot becoming a problem doing it this way without the soffit vents. Adding the soffit vents, baffles, and 2.5 inches of spray foam would cost about $900 more than just using dense pack cellulose and still not give a much better R-value than dense pack cellulose (about R-15 to R-17).
I'm having another insulation contractor look at it tomorrow, but I'd like some of your opinions.
What do you guys think?
It has about 2 inches of old fiberglass bats covering the attic floor. It has no soffit vents but there are three roof vents.
The roof was constructed using rough cut 2x4 rafters instead of the more typical 2x6 construction:
Also, the roof line actually comes down into the second floor living space:
This creates a cavity about 4 feet long and 4 inches high from the edge of the attic floor to the eave:
This winter was particularly severe and there was lots of ice damming around the roof.
An insulation contractor came over last week and gave an estimate on improving the insulation in the attic. He recommended completely filling in the cavity with either spray foam or dense packed cellulose and blowing in cellulose in the rest of the open attic space. He said that because of the way the roof is constructed, there isn't a lot of room to work with, and it isn't worth adding soffit vents. He also said that there will always be some ice damming no matter what is done, but filling the cavities would cut down on it a lot.
I'm worried about mold and rot becoming a problem doing it this way without the soffit vents. Adding the soffit vents, baffles, and 2.5 inches of spray foam would cost about $900 more than just using dense pack cellulose and still not give a much better R-value than dense pack cellulose (about R-15 to R-17).
I'm having another insulation contractor look at it tomorrow, but I'd like some of your opinions.
What do you guys think?