Best Way To Insulate Attic Ductwork

Because the simplest and cheapest way to insulate an attic is to add material to the floor.

Best way to insulate attic ductwork. Because the attic is hot it warms the surface of the duct board above the dew point temperature of the air in the attic. If you then put a layer of insulation over this surface this same surface will now begin to cool down. That s what happened to the ducts in the lead photo of this article. Use a paintbrush to apply duct mastic to the joints where an elbow.

Test total duct leakage. 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. Bury the ducts deeply in insulation.

When insulating hvac ductwork use a foil faced fiberglass insulation with an r 6 or higher r value. Mechanically fasten and mastic seal all duct connections. In humid climates burying ducts can be a risky strategy. 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.

Use the type of metallic foil duct tape recommended by the insulation manufacturer to seal and hold the insulation in place. 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. To insulate the exterior you have a choice between sleeve style insulation and blanket wraps which literally wrap around the ductwork.

For an added layer of protection you can apply duct mastic to the tape and duct. Add additional sealant if necessary. Let s use your existing duct board surface that now faces the attic as an example. 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.

Check the speed of the blower motor on the furnace. Install loose fill insulation to cover the ducts and the attic floor to meet or exceed the code required r value for attic insulation.