Does a home inspector check insulated windows for brokens seals and lost gas?
Tuesday, September 1, 2020
The Standards of Practice of the two national home inspector associations differ on what is required when examining insulated windows. The International Association of Certified Home Inspectors (InterNACHI) expects inspectors to call out any windows with clouded glass. Here’s how it is stated: "The inspector shall report as in need of correction any window that was obviously fogged or displayed other evidence of broken seals.” The American Society of Home Inspectors (ASHI), on the other hand, excludes examination for this defect: "The home inspector is not required to inspect coatings on and the hermetic seals between panes of window glass."
It’s important to note that the InterNACHI standard specifies windows that are “obviously fogged” should be caught by the inspector. Fogging of the interior surfaces between the panes of glass is due to dust deposits from the air intrusion, and it’s about the only way that the loss of insulating capability can be observed.
The problem for an inspector is that windows do not immediately become clouded after loss of their gas. It can take a year or more before the first faint evidence begins to appear and, in the early stage, can only be observed when carefully looking at the glass obliquely and/or sunlight is hitting the glass obliquely. Because of this, it is possible that evidence of the lost gas was invisible at the time of the home inspection, but becomes observable several months later by the homebuyer—followed by an angry “the home inspector should have seen this” phone call.
Repairing this defect can be expensive. It is possible to eliminate the fogging by removing one of the panes of glass, cleaning the surfaces and reinstalling the glass. Or simply leaving only one pane in place. But either solution does not regain the insulating ability of the window, which is only possible by window or sash replacement.
Also, see our blog posts How do you keep double-pane insulated windows from from getting cloudy? and Should I buy a house with double-pane insulated glass windows that are clouded? and What is causing a foggy haze on my windows? and How can I tell if a window or sliding glass door is double or triple pane (insulated) glass? and Why is pressure washing double pane windows an expensive mistake?
Click on any of the links below to read other articles about what is required to be included, or not, in a home inspection:
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• • • • • • • • • • • • • • • • • • • • • • • • • • •
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