Condensation or Moisture in Your Windows?

The basic construction of a window or Insulated Glass Units (IGUs) consists of a spacer bar and glass. The spacer bar is installed between two or three pieces of glass (i.e. “double” or “triple” pane windows) and runs around the outer edge of the glass unit. You must be alert and watch for any window condensation that builds in-between your thermal pane windows.

When the seal on a thermal pane window fails, the trapped air between the panes is pumped out as the air space heats up and expands. Humid air is drawn into the enclosed space as the window cools down and window condensation occurs.

The surfaces between the side of the spacer bar and the glass is where the IGU may have what is referred to as; “a seal failure”. Two key components of a window seal in your windows are the quality of the spacer bar and the adhesive material used to adhere or create “the seal” between the glass panes and the spacer bar.

Visible fog, condensation or moisture is a sign that the sealed window unit has simply reached Its threshold to absorb moisture, causing foggy window or condensation problems. This is a repairable and preventable condition.

The main components of a proper Window Seal.

Swiggle Seal – The patented Swiggle Seal consists of steel swiggle or continual “s” shaped plate covered by a black rubber like compound containing a foam version of the moisture absorbing desiccant silica pellet. The swiggle seal is typically about as deep as it is wide and wraps around the entire sash structure. Once again, the main function of this product is to allow the window to breathe during “Solar Pumping” and ultimately stop moisture from visibly showing or “fogging” between the two surfaces of glass. It helps to prevent window condensation from building in your windows.

Aluminum Spacer – After a closer look at the Aluminum Spacer bar you will see one or two small perforated lines running down the center of the spacer bar and around the entire inner surface. The perforated lines allow the window to functionally breathe during “Solar Pumping”. Inside the spacer bar are desiccant materials (similar to the little bag you get when you purchase a new item like; electronics, tools, shoes, purses and furniture etc.). The sole function of the desiccant material is to absorb any moisture and keep the window condensation from visibly showing or “fogging”.


Poor Caulking can lead to seal failure.

A major contributor to “seal failure” or “window saturation” is poor caulking on the outside and inside of windows. In most cases, as gravity naturally drives the moisture down to the base of the window it accumulates on the adhesive that bonds the bottom seal to the glass surfaces. Over time the internal pressure created by Solar Pumping and sustained moisture will cause the adhesive between the glass and spacer bar to separate. (i.e., seal failure). Regular maintenance like caulking, and if necessary painting, will greatly reduce seal failure, window saturation, and ultimately extend the life of the window.