Answer: Condensation between panes of glass is usually a sign of seal failure. Seal failure means that the sealant holding two panes of glass together is no longer maintaining a dead air space. Once the failure begins to allow too much air exchange within the air space, the desiccant will no longer be able to attract moisture effectively enough. Hence, you will begin to see obvious moisture, condensation, fogging or water spots within the glass. Many glass panes get some fog between the panes for very short periods of time during rapid temperature changes, hail storm events etc. especially in the Rocky Mountain Regions. This is technically a seal failure, but as long as this moisture quickly disappears, it can be considered completely normal. In most cases, seal failures require replacement of the insulated glass unit or the sash unit replacement.
