Blog by All-Star Home Inspection Services LLC.

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Leaky Ducts

Dear All-Star,

Every so often, you get a question about a home's ductwork, and I appreciate the importance you give to this area. We had huge energy bills and a home that never got comfortable until we took your advice and had our ducts inspected, which we discovered were in terrible shape. After repairing them, it's like living in a new home. Can you please write about this topic on a regular basis to let other people know what a difference it can make?

All-Star:  I guess I do keep writing about it because of all the questions I get about ducts. I get many emails that carry the same basic message - "every time we use the heat or the air conditioning for a while, our utility bills are enormous. It also feels like our home is always too humid or too stuffy." The problem is that in most homes, the ductwork - the network of insulated tubes that carry the heated or cooled air throughout the home and then back to the heating and cooling equipment - is located in the attic where you can't easily see holes or rips or tears. Unless the ducts get a thorough inspection, the problems might never be found. In the meantime, you're paying very high utility bills and always complaining about the uncomfortable home you've got. In fact, poor air quality and dust, mold and mildew all go hand-in-hand with duct leaks, so sealing the system is critical. Let's take the bad news one step further. If your home has leaky ducts and many homes do then all the potential savings and comfort you're trying to get by using CFLs, shading on windows, high-efficiency appliances and other things, will be pretty much wiped out by the duct problems. Even very tiny leaks in ducts waste energy, just as a little drip in a kitchen faucet can waste a great deal of water. It adds up very quickly. In fact, the California Energy Commission has used the analogy that connecting a high-efficiency furnace to a leaky duct system is similar to ordering a diet drink with a hot fudge sundae! Many builders these days are putting the ductwork into conditioned spaces rather than in the unconditioned attic so that losses from the ducts end up in the home's living space rather than in the attic or outdoors. It's been estimated that more than a third of the conditioned air never reaches the target rooms because of holes in the ducts. As a result, it's become pretty difficult to pick up a newspaper and not see ads for companies that inspect and clean ducts. A big new industry has developed in response to the need for sealing ducts properly. By the way, for you trivia buffs, if someone asks what is the best thing to use to seal ducts, don't say "duct tape." While duct tape has hundreds of uses around a home, sealing ducts just isn't one of them. The recommended sealant is mastic, a sticky substance that gets painted onto seams and tears and hardens for a tight seal. Why do ducts leak so often? There are lots of possible reasons, many caused by their location in the attic where things you store up there can bump into them, or even the settling of the house over time can affect them. Sometime it turns out that when the house was built, the contractor didn't properly attach the ductwork in the first place and it's been leaking for many years undetected in the attic. Properly sealed ducts will keep the conditioned air in your home where you want it. So the bottom line is that if your energy bills seem to be excessive no matter what you do to try to save energy, and if your home always feels too humid or everyone seems to be getting sick all the time or if you're constantly having problems with mold and mildew, or if the house is just plain uncomfortable all the time, it may be a good investment to bring a contractor out to inspect your ducts. One caution, though. If you hire a company to clean the ductwork in your home, get some references first and make sure they are experienced. I hear too many stories about companies causing more damage than they fixed when they tried to clean ducts. This isn't a job for amateurs.  For more information on your duct system please contact All-Star Home Inspection Services at 209-824-5356.