IG units rely on a seal around the edge two pieces of glass to keep moisture out from in between the two layers of glass. When this seal fails then windows will become foggy looking and/or have moisture streaks in between the two panes of glass that cannot be cleaned. This makes the window hard to see through and unattractive. It also means that the window has lost its energy effeciency and has a lower insulating value.
When the seal first fails your windows may not be fogging over as bad as the picture above, but they will continue to get worse.
Shane Burk Glass & Mirror can replace just the IG unit(s) that need it without having to replace the enitre window and frame. We can match any bars that you may have as well as tint and argon gas in the new replacement IG unit.