Case Studies

Attic Insulation Case Studies: Ducts In Attics-Make rooms cooler in summer, warmer in winter

Monday, March 20th, 2017 by Kevin Bailey


The rooms upstairs are hot and humid in the summer, and colder than rooms on the main floor in the winter. This customer noticed that the A/C seemed to run non stop on hot summer days. They assumed (correctly) that they needed to add attic insulation. But what this family didn't realize was that blowing insulation would not solve the problem alone. This is because the supply ducts to the rooms is located in the attic. These ducts have an R-7 wrap of fiberous material (fiberglass batt), which allows air to leak right through. Even with the vinyl facing on the duct wrap, if you're sending 55 degree cool air through ducts located in an attic that is 120 degrees (on an 80 degree summer day) your 55 degree air is going to get warmed closer to 70 degrees. As these homeowners know, an R-7 of Fiberglass duct wrap is not going to prevent this. Furthermore, the wrap has seams and gaps that allow supply air to leak out of the ducts into the attic space. There's a better way to treat these ducts 


Closed Cell Spray Foam is one of, if not the best way, to insulate. One inch of this foam and we acheive an air barrier. Meaning that with 1 inch spray to a surface, air can not pass through! So we apply 1 inch of spray foam to the ducts in the attic. We apply it to the main trunk line and to the connections at the supply registers. We also get an R-7 with one inch of spray foam. So it benefits us to keep the existing wrap on the duct and spray foam over the existing insulation. Now we have an R-14 total. And we have an air-tite and true duct encapsulation which will actually keep the air supply cool in the summer, warm in the winter. Leaving them with comforable rooms upstairs year round.

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Blanket Insulation Services
21421 Hilltop St #1
Southfield, MI 48033