Bury Ducts In Attic Insulation

The condensation issue could be addressed with higher levels of duct insulation.

Bury ducts in attic insulation.

Tim healey the 2018 iecc will allow low lying ducts in attic space with rules for each climate zone that specify insulation coverage above and below the ductwork. The best way to address poorly insulated attic ducts is to replace older flex duct with newer flex duct with a higher r value at least r 8. The insulation levels should meet or exceed the code required r value for attic insulation. Bury the ducts deeply in insulation.

This isn t equivalent to bringing them into the conditioned space as you ll still have additional duct load but it s a lot better than having them in unconditioned attic space. When hvac ducts are installed in a vented attic in a dry climate bury the ducts in attic insulation to protect them from temperature extremes in the unconditioned attic space. Water vapor from the air condenses on air conditioning ducts in humid climates. Use metal flex or fiber board ducts that are insulated to.

That s what happened to the ducts in the lead photo of this article. Figure 1 shows a duct that is encapsulated in spray foam and then partially fully or deeply buried in blown attic insulation. But in my last article i also showed you some preliminary results from a research study on buried ducts in a hot humid climate. The easiest and least expensive way to do it is to put the ducts in the attic and bury them with insulation.

Yes when you bury ducts in attic insulation in a humid climate you increase the risk of water vapor condensation on the jacket of the duct insulation. After research drumheller found that burying ductwork in attic insulation actually saves energy and the concern about condensation was only regional when employing higher efficiency levels of the new energy codes. In a hot humid climate moisture can condense on cool ducts and register boots when the air conditioning system is blowing cool air through the ducts. At least that s what dr.

If you bury attic ducts in cellulose or fiberglass insulation you need to think about summertime condensation. If you need to bury the ducts in insulation the only safe way to do it is to first install a 2 inch layer of closed cell spray foam on the outside of the ducts. It s as normal as poorly insulated bonus rooms making occupants.