Insulating Heat Ducts In Attic

Replacing your ducts is another option when you ve got old uninsulated ones.

Insulating heat ducts in attic.

Use the type of metallic foil duct tape recommended by the insulation manufacturer to seal and hold the insulation in place. Sometimes the insulation is inside the ductwork. When the attic is 20 f that insulation is addressing a delta t of 50 f. Because the simplest and cheapest way to insulate an attic is to add material to the floor.

Because the moving air is in the ductwork for only a short period of time it does not need the insulation r value the attic floor requires. 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. Of course you might also consider replacing your old ducts. Use a paintbrush to apply duct mastic to the joints where an elbow.

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. A metal duct conveying cool conditioned air through a broiling attic in summer or warm air through a chilly crawl. Acute temperatures in these areas contribute to thermal loss in metal ductwork. Wrap fiberglass duct insulation around the ducts and tape the seams together.

Press a continuous strip of foil tape to all longitudinal seams along straight runs of duct. Make sure the foil surface of the insulation is free of dust before applying the tape. Our team follows a rigorous process for replacing ductwork. Unfortunately so many houses especially newer homes end up with ductwork running through the attic.

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. So logically the ducts deserve more not less insulation. When insulating hvac ductwork use a foil faced fiberglass insulation with an r 6 or higher r value. But the air in the ducts is facing a delta t of maybe 100 f or 120 f a greater delta t.

Other times insulation may be on the outside. Check the speed of the blower motor on the furnace. Out with the old in with the new. After all most new homes have r 49 insulation on the attic floor holladay continues.

The greater the temperature extreme between the air inside the duct and the air surrounding the ductwork the greater your need for duct insulation. First consider the duct location. When hvac ducts are installed in a vented attic in a dry climate bury the ducts in attic insulation to protect them from temperature extremes in the unconditioned attic space. 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.