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Wrapped air ducts in rafters.

Is Wrapping Ductwork to Prevent Condensation Effective?

Yes, properly wrapping your ductwork is an effective method to prevent condensation. If you’ve noticed droplets of water forming on your ductwork, first rule out mechanical issues. Then wrap your ductwork with duct wrap, which is insulation made especially for insulating ducts, has an inner layer of foam or fiberglass and an outer layer of foil.

Let’s get started.

Rule Out Mechanical Problems

Before wrapping your ducts, use this checklist to help detect any condensation-causing HVAC problems:

  • Clean or replace your filter.
  • Listen for strange noises that might indicate a broken fan.
  • Smell your ductwork. A new or foul odor might indicate a blockage or a dirty filter.
  • Check for leaks. You may be able to feel air leaking out of a duct with your hand, or with the help of a pressure gauge.

If the airflow problem persists, you may have a dirty evaporator coil or the system could be low on refrigerant causing the coil to ice over causing excess drainage. Contact your local Aire Serv for professional assistance.

Prepare to Wrap Your Ducts

Once you’ve ruled out a mechanical or other HVAC issues, consider insulating your metal ductwork. Uninsulated or poorly insulated metal ducts are often the culprit. Insulation prevents warm air outside the ducts from contacting cool, metal ductwork, thereby preventing condensation. Duct wrap, which is insulation made especially for insulating ducts, has an inner layer of foam or fiberglass and an outer layer of foil.

To insulate your ducts, you’ll need the following gear, along with your insulation:

  • Protective goggles
  • Metallic foil duct tape
  • Dust mask
  • Straight edge or carpenter’s square
  • Utility knife

Wrapping Duct Work to Prevent Condensation

Once you have the right tools and materials, follow the below steps to wrap your ducts.

Here’s how:

  • Measure your insulation. Wrap the material around your ducts and mark where you’ll need to cut for a snug fit. Make sure the fit isn’t so tight that the insulation layer will be compressed.
  • Cut the insulation. Using your straight edge or carpenter’s square as a guide, cut the insulation with a utility knife.
  • Clean and apply the insulation. Wipe down the foil edges of the insulation so that duct tape will apply cleanly later. Apply small pieces of tape as you go to hold the wrapping in place.
  • Seal insulation with tape. Remove the paper backing from the duct tape as you apply it to prevent it from sticking to itself. Seal the length of each wrapping piece with a long piece of duct tape. Seal joints by wrapping tape all the way around.
  • Inspect. Check for gaps and seal everything with tape.

Still worried about excess moisture around your HVAC ducts? Help your system out by installing a dehumidifier in your attic or crawlspace. Or have your ducts spaced out farther apart to promote airflow. And, of course, replace your air filters and get your ducts cleaned regularly.

Still Have Excess Moisture?

If after following the above, you still have moisture, you will need to take additional steps, such as installing a dehumidifier in either your attic or crawlspace. Visit our page on dehumidifiers to learn more.