Best Way To Insulate Attic Ductwork

Check the speed of the blower motor on the furnace.

Best way to insulate attic ductwork.

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. In humid climates burying ducts can be a risky strategy. That s one of mike macfarland s jobs in northern california where burying ducts is a no brainer. Install loose fill insulation to cover the ducts and the attic floor to meet or exceed the code required r value for attic insulation.

To insulate the exterior you have a choice between sleeve style insulation and blanket wraps which literally wrap around the ductwork. When insulating hvac ductwork use a foil faced fiberglass insulation with an r 6 or higher r value. Use a paintbrush to apply duct mastic to the joints where an elbow. Because the simplest and cheapest way to insulate an attic is to add material to the floor.

For an added layer of protection you can apply duct mastic to the tape and duct. 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. If you then put a layer of insulation over this surface this same surface will now begin to cool down. Test total duct leakage.

Bury the ducts deeply in insulation. If necessary switch the wires to reduce the blower to its lowest. The duct insulation should include a vapor barrier cover. Press a continuous strip of foil tape to all longitudinal seams along straight runs of duct.

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. That s what happened to the ducts in the lead photo of this article. Use the type of metallic foil duct tape recommended by the insulation manufacturer to seal and hold the insulation in place. 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.

Mechanically fasten and mastic seal all duct connections. Add additional sealant if necessary.