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How much air does dense-packed cellulose leak?

I've been thinking a lot about dense packed cellulose and reading up on it's various properties. I found an excellent discussion on this same message board: http://www.greenbuildingadvisor.com/community/forum/energy-efficiency-an....

What I've learned on this discussion is that desnse packed cellulose is not considered an air barrier because it does not meet the ASTM standard for an air barrier at 0.02 l/sec-m2 or 0.004 cfm/sf @75Pa. This makes sense to me. What I'm trying to find out is if there have been any studies published about how air permeable dense packed cellulose actually is. I'd like to see numbers, and especially numbers expressed in the same form as they are expressed when talking about actual air barriers. Any ideas?


Josh Engle

Asked by Josh Engle
Posted Jun 25, 2014 7:46 AM ET
Edited Jun 25, 2014 9:25 AM ET


2 Answers

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Here is an article that address your question:

Don't Be Dense—Cellulose and Dense-Pack Insulation:

"Empty walls (a wood frame wall with plywood sheathing or a wood frame wall with board sheathing, building paper and interior gypsum board) vary [in air leakage rates] between 0.4 to 4 cfm/ft2 at 0.3 in. w.c. (2 to 20 L/s·m2 at 75 Pa) leakage. When we blow them with insulation (we dense pack them to around 3.5 lb/ft3 [56 kg/m3] density), the leakage drops to 0.04 to 0.2 cfm/ft2 at 0.3 in. w.c. (0.2 to 1.0 L/s·m2 at 75 P.5). This is unbelievably impressive.... As impressive as these numbers are, an order of magnitude reduction in leakage, we need to put these numbers into perspective. Dense pack cellulose and dense pack fiberglass are not air barrier materials, and they do not result in air barrier assemblies."

Answered by Martin Holladay, GBA Advisor
Posted Jun 25, 2014 9:04 AM ET
Edited Jun 25, 2014 9:07 AM ET.


Thanks Martin, that helps a lot.

Answered by Josh Engle
Posted Jun 26, 2014 7:36 AM ET

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