We've Been Serving Sonoma and Marin Counties for 48 Years!

New Duct Sealing Requirements

Most homes with central air conditioning and heating systems have ducts that were never properly sealed.

The average home’s ducts leak around 30 percent of the conditioned air outside the home.

  • The greatest energy use in California homes is for central air conditioning and heating.
  • These leaks are taking money straight out of your pocketbook. Properly sealed ducts will lower your energy bills, reduce pollution inside your home, and help to avoid a repeat of the inconvenience and health and safety risks that we suffered during the power blackouts in 2000.
  • As of October 1, 2005, you must have your home’s ducts tested for leaks when you have a central air conditioner or furnace installed or replaced. Ducts that leak 15 percent or more must be repaired to reduce the leaks.
  • After your contractor tests and fixes the ducts, you choose whether to have an approved third-party field verifier check to make sure the duct testing and sealing was done properly, or to have your house included in a random sample where one in seven duct systems are checked.

Duct sealing is not required in the following situations:

  • When homes are in specific coastal climates;
  • When systems have less than 40 feet of ductwork in unconditioned spaces like attics, garages, crawlspaces, basements or outside the building;
  • When ducts are constructed, insulated or sealed with asbestos. There also are specific alternatives that allow high efficiency equipment and added duct insulation to be installed instead of fixing duct leaks.

You also should know that any contractor failing to obtain a required building permit and failing to test and repair your ducts is violating the law, and exposing you to additional costs and liability.

Real estate law requires you to disclose to potential buyers and appraisers whether or not you obtained required permits for work done on your house. If you do not obtain a permit, you may be required to bring your home into compliance with code requirements for that work and you may have to pay penalty permit fees and fines prior to selling your home.

Important points to remember when having your furnace or AC system repaired or replaced:

  • Whenever a furnace or air conditioning system is installed, replaced, or more than 40′ of ducting is removed, an air leakage test is required by the city and state.
  • A 15% air leakage test is performed on all replacements of furnace or air conditioner.
  • When all-new ventilation ducting is installed, a 6% air leakage test is required. A third party is called out to perform this test. On the final day of installation, a Home Energy Rating System (HERS) rater comes to the home and performs this test. Then the paperwork is sent to you, as well as the local county or city you live in.
  • This test benefits customer by making sure the air ducts are not releasing conditioned air under the house or in the attic, wasting energy. This test makes your contractor seal all ventilation ducts to the plenums, furnace or air handlers, ensuring a very efficient system.