The rigid insulation was saturated from condensation.
How to insulate flex ductwork in attic.
Most insulation relies upon the air space between its fibers to deliver the r value promised.
Invest in duct insulation today to safeguard your family s health and your pocketbook.
Applying spray foam insulation to the outside of the duct.
The cost and effort to add more insulation is minimal.
Cover the metal ductwork with closed cell spray foam.
The foam provides a vapor barrier so the ductwork.
The flex ducts were literally filled shut with ice in the low spots compressing the scant insulation layer beneath them.
Mechanically fasten and mastic seal all duct connections.
I found instead a vintage 3 ton ac unit with 1 rigid insulation taped all over it and insulated flex duct snaking all over the poorly insulated attic.
Heaping insulation over the ducts is fine in dry climates but can cause condensation on the duct insulation jacket in humid climates.
If it s uninsulated you should insulated it to at least r 4 to r 8 for dfw.
Stop wasting money and energy with a leaking duct system.
That s what happened to the ducts in the lead photo of this article.
The first thing you want to do is take either air duct sealant or mastic and spread it around the take off.
The doe s building america program recommends beds buried encapsulated ducts.
Tape any punctures in the insulation s vapor barrier to prevent leaks.
If your rigid metal ductwork has any insulation it may already have enough.
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.
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Spread it around with either your fingers or a disposable chip brush or disposable paint brush.
By spraying closed cell foam on the ducts before burying them in attic insulation you prevent the condensation problem.
The two most common ways to insulate ductwork are.
If you need help deciding which type of insulation you need set up an energy consultation.
Consider adding more insulation as ductwork is farther from the furnace.
Avoid compressing the insulation.
Use metal flex or fiber board ducts that are insulated to code.
You re throwing money out the window.
Bury the ducts deeply in insulation.
When these ducts are exposed to exterior air the plastic jacket never gets cold enough to permit condensation because the hot attic air keeps the plastic jacket warm.
If you want to cover metal ductwork with blown in insulation t hese steps must be followed in this order.
How to insulate the attic air sealing the attic energy saving attic insulation duration.
Mastic comes in a bucket air duct sealant comes in a tube they re basically the same thing.
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Install ductwork so that it is in direct contact with i e laying on the ceiling and or truss lower cords.
Most attic ducts are insulated flex ducts that is flex ducts with r 6 or r 8 fiberglass insulation along with an exterior polyethylene jacket.
