The more insulation you install the less likely you are to have condensation in the ductwork.
Insulated dryer duct in attic.
How to insulate your attic duct system step by step with video instructions as winter nears many will begin to activate their home heating system to keep the house warm in the blustery and frigid temperatures that accompany the change in seasons.
Attach the insulation with a high quality reinforced foil duct tape.
Wrap everything including any pliable sections near the dryer and secure it with the tape.
Do not use sheet metal screws to connect the ductwork because the screw tips protrude into the duct and will collect lint.
Insulation that s carefully wrapped around the duct will work better than fiberglass batts just piled on top.
Finally caulk around the opening where the pipe vents to the outside to prevent any cool air from sneaking in.
Doing so would fill your attic with warm moist air that could rot the framing.
The effective r value of a buried duct installation depends on the size of the ducts the r value of the duct insulation and the depth of the loose fill insulation.
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.
Table 1 shows effective r values for 8 inch round ducts at three attic insulation levels and three duct insulation levels r 4 2 r 6 and r 8.
The international residential code allows you to run a dryer vent through the attic but you can t terminate it there.
Standard duct tape can heat up and fail over time so get the good stuff.
Of fiberglass insulation will keep the duct warm during dryer operation and will minimize condensation on the duct walls.