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Duct location, unvented attics

In the Building Science America series unvented attics are recommended; "as long as they have airtight ceilings and the ductwork is not in unconditioned space". So how do you put in ductwork in conditioned space? I don't really want to use spf around the whole ductwork. Burying it in FG or cellulose doesn't keep it from causing condensation when it carries the air conditioning. Where is the ductwork to be placed?

Asked by Michael McKinley
Posted Nov 24, 2012 1:04 PM ET

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4 Answers

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1.

Between floors in open web floor trusses.

Answered by John Semmelhack
Posted Nov 24, 2012 3:02 PM ET

2.

Michael,
Here's an article that addresses your exact question: Keeping Ducts Indoors: Five ways to bring ducts inside a home’s conditioned space.

Answered by Martin Holladay, GBA Advisor
Posted Nov 24, 2012 4:05 PM ET

3.

Is an unvented attic recommended if we have ducts in the attic, but we do not have air conditioning. We live near San Francisco so outdoor temps rarely exceed 80 deg F. Right now we have a rectangular house with a pitched roof and gable vents on either end. Given that heating energy is our biggest concern, should the attic be vented or unvented?

Answered by chris Y
Posted Nov 24, 2012 5:03 PM ET

4.

Chris,
It always makes sense to keep your ductwork inside your home's conditioned space. It makes no difference whether the ducts are used for heating, or air conditioning, or both.

If your ducts are located in your attic, you want an unvented conditioned attic. Your heating system will perform better and will be more efficient if you have an unvented conditioned attic than if you have a vented attic.

Here is an article with more information: Creating a Conditioned Attic.

Answered by Martin Holladay, GBA Advisor
Posted Nov 25, 2012 7:03 AM ET
Edited Nov 25, 2012 7:04 AM ET.

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