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insulation integrity

insulation integrity

New postby Dennis on Sun Nov 07, 2010 7:49 am

In a attic with blown insulation R-value at 30, the a/c ducts are stapped above the bottom truss right above the ceiling, is there a problem with the a/c ducts and insulation, with the code? Located in Florida.
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Re: insulation integrity

New postby Jerry Peck - Codeman on Sun Nov 07, 2010 7:31 pm

Hi Dennis,

The ducts should be either under, or above, the insulation, not "in" the insulation.

As you describe the ducts on the top of the bottom chords, the insulation will not meet the require minimum R-value, which is based on inches of thickness for the different insulation materials. The insulation certificate (usually stapled to a truss at the attic access and visible when you remove the attic access access cover) will state the minimum thickness for a given R-value for that insulation. That is the *minimum* thickness for that insulation.

Also keep in mind that the attic access cover must also be insulated to the same R-value as specified for the rest of the attic, as well as any vertical wall areas (down to drop soffit, up to higher ceilings, etc.) - those vertical wall areas are required to also meet the R-value specified for the attic ceiling, not just wall insulation R-value.

Your blown in insulation will also require insulation dams at the soffits to the soffit vents and around the attic access opening.
Jerry Peck - CodeMan
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