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Seal Exposed Ductwork

Brian Gregory

By Brian Gregory
Updated May 13, 2020

Learn how to seal exposed ductwork in your furnace and air conditioner with these tips.

Skill

Intermediate

Time

One Day

Sealing Ductwork.

Tools and Materials

Note

Product costs, availability and item numbers may vary online or by market.

Identifying Leaks

Ductwork is the system in which conditioned air is transported to heat or cool your house. In an average home, up to 20 percent of that air is lost due to leaks, holes and faulty connections. Look for tiny holes in the tubing, gaps and branching lines of dust and dirt at duct connections. Most problems are found at the duct joints, duct connections and where ducts meet an air vent or floor register.

Below are signs your ductwork may need attention:

  • High summer and winter utility bills
  • Rooms that are difficult to heat and cool
  • Stuffy rooms
  • Poor air quality, such as excessive dust

 

Caution

Ductwork can be hard to access. If you don't feel comfortable making repairs, contact a professional.

Before You Shop for Materials

  • Check to see how much of your ductwork is accessible from the basement, crawlspace or attic.
  • Check whether ducts are made from sheet metal, fiberglass, flexible tubing or a combination of these. Tape works especially well on fiberglass and flexible ducts as well as flat metal ducts; liquid duct sealant provides a tight seal around odd-shaped metal joints.
Caution

Wear eye protection when sealing ductwork. You’ll be working in dusty conditions and, in the case of sealant, brushing on liquids overhead. Wear disposable latex or nitrile gloves when using liquid sealant.

Tape Ductwork

Instructions

Use Duct Sealant

Follow these steps to use duct sealant.

Instructions

Benefits of Sealing Ductwork

Ensuring your ductwork is properly sealed can:

  • Save money on energy costs
  • Make room temperatures more comfortable
  • Improve indoor air quality
  • Protect the environment by using less energy
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