How To Insulate Ductwork In Attic

The duct insulation should include a vapor barrier cover.

How to insulate ductwork in attic.

Because the simplest and cheapest way to insulate an attic is to add material to the floor. The foam provides a vapor barrier so the ductwork won t sweat. Cover the metal ductwork with closed cell spray foam. It was new when the ac was put in 7 years ago.

Use metal flex or fiber board ducts that are insulated to code. Cover the spray foam with fire retardant spray. When insulating hvac ductwork use a foil faced fiberglass insulation with an r 6 or higher r value. Recently i had another hvac company come out and put in a new bathroom vent and they told me they believed the duct work was full of water.

Use a paintbrush to apply duct mastic to the joints where an elbow. 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. Bury the ducts deeply in insulation. How to insulate the attic air sealing the attic energy saving attic insulation duration.

But if the floor is covered in plywood you can t stuff enough insulation beneath it to do the job sufficiently not even in warm climates. The attic ductwork is flex duct work. Energy saver dealers 204 202 views. 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.

Use a pressure sensitive vapor retarder tape designed for ductwork. Use the type of metallic foil duct tape recommended by the insulation manufacturer to seal and hold the insulation in place. Install ductwork so that it is in direct contact with i e laying on the ceiling and or truss lower cords. If you want to cover metal ductwork with blown in insulation t hese steps must be followed in this order.

I called out the original hvac company and they took a look and said they saw no water. Most insulation relies upon the air space between its fibers to deliver the r value promised. Plan to pull up the flooring and layer new insulation on top of the old. Tape any punctures in the insulation s vapor barrier to prevent leaks.

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. Mechanically fasten and mastic seal all duct connections. Avoid compressing the insulation. Press a continuous strip of foil tape to all longitudinal seams along straight runs of duct.

If necessary switch the wires to reduce the blower to its lowest.