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Loose-pack versus dense-pack cellulose for a flat roof

Loose-pack cellulose has been recommended for the cockloft of our row house. The roof has a slight grade so that the cockloft height goes from about 1 foot to 2 feet (including the roof joists). We will have a vapor permeable air barrier below it. Is loose fill a better choice here than dense pack? If so, why?

Asked by Daniel Herskowitz
Posted Wed, 12/11/2013 - 00:11
Edited Wed, 12/11/2013 - 07:59


2 Answers

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To read my recommendations for insulating this type of roof, see Insulating Low-Slope Residential Roofs.

Your attic isn't high enough for a vented approach, so you will need to create an unvented roof assembly.

Unvented roof assemblies require either rigid foam on top of the roof sheathing (an approach that requires you to install new roofing) or spray foam insulation on the underside of the roof sheathing. All of the necessary details for a successful unvented roof assembly are described in my article.

Don't forget to insulate your attic walls.

Answered by Martin Holladay, GBA Advisor
Posted Wed, 12/11/2013 - 07:21

Helpful? 0

Local climate affects the answer- where are you?

Answered by Dana Dorsett
Posted Wed, 12/11/2013 - 14:24

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