Best Way To Insulate Attic Ductwork

For an added layer of protection you can apply duct mastic to the tape and duct.

Best way to insulate attic ductwork.

In humid climates burying ducts can be a risky strategy. Test total duct leakage. When insulating hvac ductwork use a foil faced fiberglass insulation with an r 6 or higher r value. If necessary switch the wires to reduce the blower to its lowest.

Plan to pull up the flooring and layer new insulation on top of the old. Press a continuous strip of foil tape to all longitudinal seams along straight runs of duct. Use a paintbrush to apply duct mastic to the joints where an elbow. Air sealing all the ducts and air handler connections and seams and air sealing all the duct boots to the ceiling gypsum and any other penetrations is a critical first step prior to adding any insulation.

Because the simplest and cheapest way to insulate an attic is to add material to the floor. If you then put a layer of insulation over this surface this same surface will now begin to cool down. 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. Bury the ducts deeply in insulation.

The best way to do buried ducts unless you live somewhere where you have to worry about ice dams is to close up the soffit vents and replace the ridge vent with a diffusion vent i see prescriptive practices regarding diffusion venting have been addressed in the irc 2018 at least for us climate zone s1 2 3. Check the speed of the blower motor on the furnace. Add additional sealant if necessary. Mechanically fasten and mastic seal all duct connections.

Let s use your existing duct board surface that now faces the attic as an example. Install loose fill insulation to cover the ducts and the attic floor to meet or exceed the code required r value for attic insulation. The duct insulation should include a vapor barrier cover. Use the type of metallic foil duct tape recommended by the insulation manufacturer to seal and hold the insulation in place.

Because the attic is hot it warms the surface of the duct board above the dew point temperature of the air in the attic. To insulate the exterior you have a choice between sleeve style insulation and blanket wraps which literally wrap around the ductwork.