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Deciding between blown-in or spray foam attic insulation

13 years ago

I live in a 1945 brick colonial in Northern Virginia. As soon as the temps go down, you can really feel the cold in our upstairs. We've started looking into improving the attic insulation and now I'm totally confused. This house is small with minimal storage space. The attic is floored and is one of our main storage spaces, and there is already insulated under the attic floorboards, but it is only about 5-6 inches high. Best guess is that our current R-value is around 10.

We've had a few insulation companies give us estimates. The main question is how do we keep the storage space and raise the R-value of the insulation???

One way seems to be to make the attic a conditioned space and spray foam along the slope. The attic will then be conditioned and completely closed and unvented (oh yeah, old home with just one vent at one end and an attic fan at the other. No soffits or ridge vents).

The other alternative we've gotten is to blow in insulation to build up the insulation around the edges of the attic that are not floored in and then just leave the floored area as it is.

The price difference is significant. Spray foaming is 3x the blown in. But what about the attic being unvented? What about air sealing? The spray foam guy explicitly included air sealing in the estimate and discussed it as an issue.

At this point we don't know how to make a decision. Make the attic a conditioned space w/spray foam or just improve what insulation we can?

Any advice greatly appreciated!!!!

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