Minor Duct Repair Tips
Check your ducts for air leaks. First, look for sections that should be joined but have separated and then look for obvious holes.
Duct mastic is the preferred material for sealing ductwork seams and joints. It is more durable than any available tape and generally easier for a do-it-yourself installation. Its only drawback is that it will not bridge gaps over ¼ inch. Such gaps must be first bridged with web-type drywall tape or a good quality heat approved tape.
If you use tape to seal your ducts, avoid cloth-backed, rubber adhesive duct tape — it tends to fail quickly. Instead, use mastic, butyl tape, foil tape, or other heat-approved tapes. Look for tape with the Underwriters Laboratories (UL) logo.
Hire a Licensed HVAC professional to install both supply and return registers in the living area.
Be sure a well-sealed vapor barrier exists on the outside of the insulation on cooling ducts to prevent moisture condensation.
If you have a fuel-burning furnace, stove, or other appliance or an attached garage, install a carbon monoxide (CO) monitor to alert you to harmful CO levels.
Be sure to get professional help when doing ductwork. A qualified professional should always perform changes and repairs to a duct system.