Bury Ducts In Attic Insulation

At least that s what dr.

Bury ducts in attic 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. Figure 1 shows a duct that is encapsulated in spray foam and then partially fully or deeply buried in blown attic insulation. For builders following the performance path buried ducts may be considered as insulated to r 25 and sufficiently well sealed ducts may be treated as located within the conditioned space. That s what happened to the ducts in the lead photo of this article.

The easiest and least expensive way to do it is to put the ducts in the attic and bury them with insulation. The insulation levels should meet or exceed the code required r value for 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. Use metal flex or fiber board ducts that are insulated to.

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. 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.

They found r 8 duct insulation was sufficient to prevent. If you bury attic ducts in cellulose or fiberglass insulation you need to think about summertime condensation. It s as normal as poorly insulated bonus rooms making occupants. Bury the ducts deeply in insulation.

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. Water vapor from the air condenses on air conditioning ducts in humid climates. Install ductwork so that it is in direct contact with i e laying on the ceiling and or truss lower cords.