roof vent

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How to Build an Insulated Cathedral Ceiling

Whether you decide to make it vented or unvented, get the details right — because every cathedral ceiling offers opportunities to make big mistakes

Posted on Nov 18 2011 by Martin Holladay

UPDATED on December 15, 2017 with new information on R-valueMeasure of resistance to heat flow; the higher the R-value, the lower the heat loss. The inverse of U-factor. requirements.

Although the GBAGreenBuildingAdvisor.com website already contains many articles on the topic, we continue to receive frequent questions about the best way to insulate a cathedral ceiling. It’s therefore time to pull together as much information on the topic as possible and publish it in one place, to clarify the building science issues and code requirements governing insulated sloped roofs.


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Image Credits:

  1. Peter Yost
  2. Fine Homebuilding

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Can Cellulose be Used in an Unvented Roof?

Without ridge or soffit vents, the concern is moisture accumulation

Posted on Oct 31 2011 by Scott Gibson

Dean Manoogian has a Cape Cod style house in Portland, Maine, and is puzzling over the best way to retrofit the roof with rigid foam insulation.

Working with both an insulation company and a roofing contractor, Manoogian has come up with a plan: apply 2-in. rigid foam on the interior of the dormered roof and then fill the rafter bays with dense-packed cellulose.


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Lstiburek’s Rules for Venting Roofs

You need an airtight ceiling, lots of air flow, plenty of soffit vents, and deep insulation at the attic perimeter

Posted on Jul 24 2011 by Joe Lstiburek

Building Science Fundamentals: Roof, Part 1: Ventilation

By Dr. Joseph Lstiburek

Dr. Joseph Lstiburek talks about the not-so-controversial ways to maximize the efficiency and airflow of your roof and attic.

Video Transcript:
There’s been so much stuff said about roofs that you sometimes lose perspective. I’m going to start off by saying what might seem controversial but really shouldn’t be.


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