DIY Furnace Duct Insulation

Furnace ducts are typically constructed of thin metal. The thinness allows the air to lose heat as it moves from the furnace, through the ductwork, and into your home. The air that finally reaches your living area isn't as warm as it could be because of the heat loss during its travels. This heat loss costs you energy dollars. On top of that, rooms that are located farthest from the furnace are typically colder during the winter months. That's because the warmed air has farther to travel and loses even more heat. You can remedy this problem by insulating the heat ducts.

Measuring tape
Insulation
Protective clothing
Cotton gloves
Knee pads
Dust mask
Eye goggles
Work light
Extension cords
Screwdriver
Self-tapping metal screws
Duct tape
Utility knife

Instructions

- 1
  Measure the clearance around the furnace ducts to determine how thick the insulation you use can be. R-11 is recommended. Choose the highest R-value in insulation that will fit.
- 2
  Put on a long-sleeved shirt, long pants, gloves, knee pads, a dust mask and eye goggles to protect yourself.
- 3
  Inspect the joints in the furnace ductwork to make sure it's joined together tightly. Tighten or install metal screws to secure loose connections. Check the wire hangers that hold the ductwork in place to ensure they are secure.
- 4
  Use duct tape to cover all cracks, gaps and seams in the furnace ductwork. Tear the tape off in strips, then apply it.
- 5
  Measure around the first piece of duct you're insulating, starting at one end, to determine the circumference. Measure and cut a piece of insulation with a utility knife to fit.
- 6
  Wrap the insulation around the duct so it's snug. Overlap the side seams and secure them together their entire length with duct tape.
- 7
  Apply the next piece of insulation by overlapping the end over the first piece you applied and sealing it with duct tape. Keep applying insulation and moving along until the entire duct is covered.

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