Is a Foggy Window a Defect?

richmond foggy windows

The Home Inspector Perspective

One of the most interesting, and sometimes difficult question that I get asked when presenting an issue is “is that a defect?” It’s a legitimate question. Negotiations are going to take place after the inspection, and from what we understand, you can’t ask for items to be repaired that aren’t defects. For example a 20 year old HVAC system that is working is important information to have, but it is not a defect. Most of the times, it’s pretty cut and dry, but there is something about a foggy window that drives opposing parties nuts. Wars have been started over less controversial issues.

So, let’s attempt to get to the bottom of the this. Windows are typically used for three functions; to provide light, to provide ventilation, and to provide emergency escape and rescue openings, when required. Most people agree when a window is failing to provide one of these functions, it’s a defect. When there’s condensation between the panes, that’s when it gets a little foggy. (Pun intended. I crack myself up).

To keep this short, double paned windows are often filled with an inert gas, typically argon, to decrease the U-factor.  U-factor is the measure of the rate of heat transfer through the window. Lower is better. A typical double paned window, filled with argon gas will have a U-factor of .25-.30. (.35 U factor is the maximum allowed in Richmond). A foggy window is caused by seal failure, and the escape of some, or all the argon gas. One the argon gas starts to escape, air and moisture get in, the desiccant becomes saturated with moisture, and condensation and staining form between the panes. A double paned window filled with air has a U-factor of around .5. In other words, a foggy window could be allowing up to almost twice as much heat to transfer through it. In the grand scheme of things, its not a terrible amount as windows are not great insulators against heat loss any way.

It’s hard to argue that a window with a failed seal, losing, or emptied of it’s argon gas, and not thermally performing as intended, isn’t a defect. It may not be the end of the world, or a show stopper, but it’s a defect.

The good news is that failed windows don’t typically need to be replaced. The first thing to do is check if they are under warranty. If you, or the seller of the house are the first owner, you may be able to get the window sashes replaced for free. If they aren’t under warranty, the glazing assembly can typically be removed and replaced, by local glass repair companies.  The cost per window is typically around $150-$200 but, can be more, or less, depending on the size and style of window.


For more interesting info about windows, check out 4 Secrets Window Salesman Don’t Want You to Know.