Heating Duct Insulation in Unheated Basements

air duct on floor wrapped in metalic coated insulation

Unheated basements with heating ducts require duct insulation to save money on heating and air conditioning costs. When a duct is not insulated, hot air can escape into areas that do not need to be heated, such as crawl spaces, attics, and the basement itself. The heat may not adequately reach all the living space. Thus the heat will be turned up, wasting energy and raising the heating bill.

The Energy Efficiency and Renewable Energy office of the US government (EERE) says to expect to lose as much as 30 percent of the energy used to cool and heat a home due to uninsulated ductwork. Duct insulation will also help to keep in the cool air if you have air conditioning. Not only should the ducts be insulated, but make sure they are properly sealed as well.

Types of Heating Ducts

There are a few different kinds of heating ducts, including round or pipe and rectangular shaped. Some ducts are installed by overlapping sections, while others are sleeve-fitted together. Each section is then screwed together and may also be taped at the seams for a better seal and to improve the connection. You may apply duct sealant to the screw holes for optimum results.

Duct insulation is low cost, easy to install, and provides a moderate level of insulation. Local home improvement stores and hardware stores sell duct insulation, which can come in several varieties. Circular or spiral wrap duct insulation is very popular, but if you have rectangular ducts, the spiral wrap can be cut and taped onto the duct.

Always check to make sure the ductwork is sealed before placing insulation around it. If the ductwork is not sealed properly, any leaks will damage the insulation because it will create humidity. In turn, humidity can condense in the cold areas of the basement and can cause rot and mold, matting down the insulation and reducing its effectiveness.

heating duct insulation

Dangers to Duct Insulation

There are some dangers to be aware of when replacing old duct insulation. Older homes may have asbestos insulation surrounding the ductwork, which looks like grayish or yellow paper. Asbestos is severely toxic if inhaled or touched. If you suspect that your ductwork is insulated with asbestos, stop working and call an HVAC contractor or a licensed asbestos removal company to properly handle and dispose of the old asbestos insulation.

Fiberglass duct insulation was also used many years ago and is not a good option anymore. Small strands of fiberglass can get into the ducts and travel into the living spaces. This will post a problem when people breathe in fiberglass fibers.

Non-Metallic Ductwork

Many new homes or newly remodeled homes have non-metallic ductwork that is already insulated. In this instance, there is no visible insulation wrapped around the outside of the ducts. This type of ductwork is not as efficient as metal ductwork with wrap-around insulation. To add additional insulate properties, add more insulation on the outside of the ducts after making sure that the ductwork is properly sealed.