How To Insulate Heating Ducts In Attic

Come in pre measured lengths.

How to insulate heating ducts in attic. Check the speed of the blower motor on the furnace. Press a continuous strip of foil tape to all longitudinal seams along straight runs of duct. Inspect the span of ductwork to be insulated. Use the type of metallic foil duct tape recommended by the insulation manufacturer to seal and hold the insulation in place.

If necessary switch the wires to reduce the blower to its lowest speed. Install loose fill insulation to cover the ducts and the attic floor to meet or exceed the code required r value for attic insulation. Measure each run of exposed duct in an attic basement or under a subfloor. The rigid insulation was saturated from condensation.

When insulating hvac ductwork use a foil faced fiberglass insulation with an r 6 or higher r value. 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. For an added layer of protection you can apply duct mastic to the tape and duct. Obtain foil face fiberglass insulation based on the sizes.

That s what happened to the ducts in the lead photo of this article. Look for signs of air leaks at seams or joints such as streams of dust. To install sleeves you must either disassemble the ductwork and slide it on before reassembling the ducts or as many homeowners find themselves doing slit it and wrap it around like the blanket style material. They may have an adhesive strip to make the installation a little easier.

Measure the size of all square rectangular or circular ducts. How to insulate the attic air sealing the attic energy saving attic insulation duration. 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. Don t use standard cloth duct tape on hvac ductwork since the adhesive won t hold up to extreme temperatures.

In the end it s probably best to buy the blanket insulation. She asked me to go into the attic to find the roof leaks or where the snow is blowing in through the soffits. Bury the ducts deeply in insulation. Use a paintbrush to apply duct mastic to the joints where an elbow connects to a duct.

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 using this technique in a humid or marine climate the ducts must be encapsulated with spray foam before installing the blown 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.