Failed Window Unit

February 25th 2003
Failed Window Unit

Question from Jack -----

Dear Shell,

I've got a problem with moisture in between a large double-pane window. Is there any remedy besides replacing the window?



Dear Jack,

Moisture between double pane insulated glass windows indicates that the spacer bar has failed. The spacer bar separates (and provides a seal between) the outside and inside panels of glass. Most window manufacturers use an aluminum spacer bar.

If you look between the glass panels you will see an aluminum strip with perforations. This spacer bar is filled with a desiccate (moisture absorbing granular product) to remove any residual moisture between the panels during manufacture of the window. Over time, severe expansion and contraction (most commonly on south and west elevations of the home) can fracture the seal between the spacer bar and the glass allowing moisture or damp air (high humidity) to get between the panes of glass.

Over the years, the desiccate loses its ability to absorb moisture and allows moisture to appear between the panes of glass. When this happens it is usually time to replace window. You can however, depending on the type of window frame, get a glass company to make use of the existing frame and just replace the glass and spacer bar.

Consider using Low E squared with argon "Smart Glass". With an R-value of R-4.17 Smart Glass windows are very effective in reducing energy loss in the winter as well as heat energy gain in the summer months on south and west elevations. My advice is to use smart glass on all elevations for maximum energy savings. Check with your local glazing companies.

It's Just That Easy!