Doors and Windows

Windows and Doors often get the bad rap of being the worst problem affecting the comfort of a home, and that the only way to fix them is to replace all of them throughout the house.  While it is true that windows and doors are often the weakest parts of a house that separate the living space from the outdoors, improvements can typically be made to them inexpensively to achieve similar performance as brand new models.

Doors – Don’t Replace, Weather-strip

The largest deficiency, when it comes to doors, is a poor air seal around the door when it is closed. Most of the time, this is caused by the weather-stripping failing over time or being damaged. Sometimes the weather-stripping is ok, but the door doesn’t swing and close correctly because it was installed improperly or the house settled over time. Nearly every door commonly found in homes can have the swing and closure adjusted and the weather-stripping replaced with modern foam style weather-stripping that will create an air tight seal and last well over 10 years.

From an Insulation perspective, modern top of the line fiberglass or foam core insulated metal doors achieve an insulation value of less than 25% of the current building code requirement for walls compared to older doors which are between 10 and 20%. That means they are basically a hole in a home’s insulation barrier. While they can be improved by replacing the door, the improvement is typically relatively small in comparison to the insulation levels around the entire house. In addition, the installation of an air tight storm door improves the insulation value of a door assembly by about 5%.

So because it is inexpensive to make an old door seal tightly, and the insulation improvement with replacing it is relatively small, it is nearly always more cost effective to weather-strip a door then to replace it.


Like doors, the biggest deficiency for windows is the poor seal around their perimeter.  Many times the primary source of leakage is around the outside of the window where the casing trim meets the drywall.  Sealing air leaks at this point is an inexpensive fix that makes a big difference in how much air comes in around the window.  Sometimes the leakage occurs at the window sash which is more difficult to seal while still allowing the window to operate normally, but it can typically be done cost effectively.

Windows are actually worse from an insulation perspective then even older doors.  New ENERGY STAR® rated windows achieve about 14% of the insulation value of the surrounding wall, whereas standard double pane windows average about 9% and single pane windows are near 5%. So windows too are basically a hole in a home’s insulation value and while the improvement from a single pane window to an ENERGY STAR window will improve the efficiency of a home the high investment cost typically makes it less cost effective than other improvements.

In general, we recommend improving the seal around windows to improve their efficiency rather than replacement because there are typically other improvements to be made to the house which will have a greater impact on comfort and energy use with less of an investment.


An Atlas Energy Auditor can determine if sealing your band joist will help you meet your goals of comfort and energy efficiency while minimizing investment costs and time.

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