Insulating rim joist where joist cavity is used for a cold air return.
Jeremy Tesch| Posted inGeneral Questionson
One of the conclusions of a blower door test was to insulate the rim joist with spray foam. Unfortunately there is a cold air return duct that runs length of one side of the house in the cavity shared with the rim joist.
Is there a way do handle this effectively without adding a new duct? I assume spray foam cannot be added inside this space as is.
Zone 5a
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Replies
Jeremy,
The best solution is to move the duct.
Is this a 1 or 2 story home. In a 2 story an exterior wall cavity may also be used. If it is a single story home it is easy to move.
Robert,
I disagree. Exterior wall cavities should never be used for ductwoork.
Robert is saying the rim joist duct might be feeding an exterior wall stack. He's not saying it's OK.
This is a 2-story 1940s home. The return duct feeds two intakes on the first story and one or two from the second, which I believe are via wall cavities unfortunately. The first floor near the wall is always cold in the winter, mostly I assume because of the cold air return/joist. Thanks for the feedback.
In that case you'll need to move both the crawl space duct and those to the second floor. If you're serious about your insulation upgrades it's time to bite the bullet.