What causes a seal failure in insulated glass?

An insulated glass unit is described as two panes of glass with a spacer between that is filled with desiccant. An adhesive material, commonly known as sealant, is used to seal the glass and spacer together, creating an airtight seal.

When the sealant breaks, the insulated glass unit is exposed to outside elements. This can cause condensation and debris to develop in the airspace of the insulating glass unit causing a seal failure. You may notice the glass fogging up between the panes, there may be rust around the spacer, the spacer may crack or crumble, and if the glass unit has Low e glazing you will see delamination on the glass.

Many factors can cause damage to the sealant including;

• Prolonged exposure to heat from the sun

• High winds and other weather events that put pressure on the glass

• House settling

  
  

All of the above events cause expansion and contraction of the window frame. Over time this causes the seal on the insulated glass unit to deteriorate and fail. At first you will see a fog between the panes of glass. If not rectified, eventually the glass can warp, collapse inward or crack. Your window is no longer sealed and therefore not doing its job.

Many people ask if it's possible to simply re-seal their existing glass unit. Unfortunately, it's not. The glass will most likely break when trying to fully separate the unit. If the spacer is rusted, cracked or crumbling it would need to be replaced. Insulated glass units are factory built in a controlled environment using high quality sealants and materials.

If the sole issue with your window is the failure of the glass, replacing the insulated glass unit is a wise choice. As long as the window functions properly, the frame is free of rot, and the lock mechanisms work, replacing the glass unit offers a cost-effective solution.