Insulating A Bay Window Sill

The average home in the U.S. consumes 2 to 3 times more energy than needed, mainly because of insufficient insulation and lack of proper air sealing. These building envelope deficiencies are usually originated during construction. Whether it is a home built many years ago, when energy prices were not a concern, or a house that was just built, you are bound to find the same types of problems -- unless the builder is trained in green building practices and the house is "green" certified.

Besides failing to provide adequate insulation in some key areas like the attic or the basement, the average builder tends to overlook gaps in the envelope left by some architectural features, such as cantilevers, rooms above garages, and bay windows.
Dr. Energy Saver technicians are trained and certified to inspect these overlooked details and locate sources of energy waste in places where most contractors won't think about looking.

In episode 67of the On the Job Series, Larry Janesky, owner and founder of Dr. Energy Saver, walks us through the process of insulating a bay window sill in a relatively new home.

The owner of this house was complaining about drafts and cold air in the room with the bay window. While window manufactures are doing their best to provide more energy-efficient windows, with features such as double pane and low-E glass, it's important that the windows are installed correctly, with proper insulation and air sealing around the frame and sill. Unfortunately, as this video shows, that is not the case in many homes with bay windows.

The window here was sitting on an unsealed and uninsulated sill board, partially exposed to the outside. During the winter, heat was being lost to the outside through the sill and cold air was pouring in through the many gaps around it. A cold window in a warm room creates a convective loop which in turn contributes to even greater discomfort.

For this particular project, Dr. Energy Saver chose to insulate the bay window sill with SilverGlo rigid foam board insulation. SilverGlo is a graphite-infused insulation board. The graphite drives the R-value per inch of the foam up by 24% over conventional foam, by lowering its thermal conductivity. Once the insulation board was cut-to-size, installed, and air sealed, plywood and a 6-inch vinyl skirt board were installed to protect the insulation and give the window assembling a finished look.

Dr. Energy Saver dealers are out every day, all across the US, helping homeowners solve all types of energy problems and make their homes more comfortable, with improvements that pay for themselves by significantly reducing heating and cooling costs.

To learn more about our services, you can watch our other videos, subscribe to the channel for the latest updates, or visit our website to locate a Dr. Energy Saver dealer in your area.