Well if they re not properly sealed they are.
How to seal ductwork in attic.
Then use a paintbrush to apply duct mastic to the joints where an elbow connects to a duct.
Use a continuous strip of foil tape to seal off all longitudinal seams along the straight runs of the duct.
I make sure to keep that insulation away from the adhesive face so i don t contaminate it.
Liquid duct sealant provides a tight seal around odd shaped metal joints.
Check whether ducts are made from sheet metal fiberglass flexible tubing or a combination of these.
Air duct sealing video transcript.
Possibly in an unfinished basement.
You all have duct work either in your attic or crawlspace or something like that.
Apply a generous amount of sealant mastic over the thermal leak.
Make sure the duct is secure in place.
To seal ductwork the old fashioned way.
Don t use duct tape.
Steps to sealing attic air ducts locate the source of the thermal leaks by inspecting the ductwork while the air conditioner is running.
This tape is known as foil tape and it s specially made for working on your furnace or your ductwork.
This pasty thick paint like substance can be applied to cracks and gaps in your ductwork with a caulking gun and spread with a paintbrush or if using a gallon pail just scooped and applied directly with the paintbrush.
Tape works especially well on fiberglass and flexible ducts as well as flat metal ducts.
To apply insulation measure the circumference of the duct.
The tape and the caulk stick a lot better when there isn t a lot of dust there.
After you have cleaned the surface simply place a strip of the aluminum foil tape over the leak or use your mastic sealant and a paint brush to seal it.
Duct sealant is another product that is commonly used to seal up duct leaks.
Before you do anything grab your rag and make sure that the area is clean before applying either mastic sealant or foil tape.
Duct sealing by michael church here and in this video we re going to show you how and why it s very important to air seal the run of the ductwork.
Use zip ties to secure any loose ducts to the attic floor.