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One constant issue with RVs over the years since double pane were introduced in 1994 has been their propensity to "fog up” or lose their seal. These windows are truly dual panes of glass separated by an air space which technically is a thermopane however they are constructed in a different way from those used in residential applications. Having experienced this window fogging on a few coaches and knowing several others that have also experienced the problem I thought I would investigate the alternatives. This article is the second in the series. In Part one I examined repairing the existing window. In this Tech Tip I’ll review the replacement of the window glass.

Replacing Existing Windows

The second approach that I examined was complete replacement of the glass panel with new glass installed into the existing metal frame. The company we contacted about this work was Darren Thomas Glass (http://darrenthomasglasscompany.com/) in Sebring, Florida. This firm had a Vendor booth at the South East Area FMCA Rally in Brooksville and showed samples of their work which looked very well done. Arriving at their facility, you are provided with an electric hookup.

They begin by inspecting the existing window. They then remove the window, disassemble it and replace the complete glass assembly. Each portion of the window must be replaced thus if there is a single opening panel combined with one or more fixed panels, all are replaced. This makes sense, since the color of the window tinting will be slightly different than the original. Replacing all panels maintains a uniform appearance. The glass that is used is tempered laminated safety glass, identical to that used in a windshield. The contrast to the original glass is notable. It is heavier, (which may be a factor to consider on vertically opening windows) and demonstrations of hitting to break the glass yield a window that is almost impossible to smash to enter, keeping most of the shards of glass in the plastic layer between the two layers of glass. There is no air space.

The existing glass is used as a template and a new panel is precision cut to match. Edges are ground and polished and when completed, re-fitted into the metal frame. This takes time since each pane is replaced however the workmanship is excellent. The removal and reinstallation process is similar to that described in Tech Tip #78. Warranty is 100%, Never Fog again. It is said that taking this approach yields a quieter and cooler interior and based on the thickness of the glass I can see the point. You do, however lose the slight air trapped between the panels of the original. The only time that may be a factor is in high humidity, rapid temperature change conditions where fogging of the interior window may occur. If you relate it to your automotive windshield, where defroster vents provide heated dehumidified air to quickly dissipate any interior fogging you get the point. That may be a consideration if a driver or passenger front side windows are replaced where the ability to see mirrors under those conditions is critical. The cost for the glass replacement is based upon the square footage of glass replaced. On the surface the cost is slightly higher, certainly competitive when the fact that taking this approach will never require the window to be removed due to fogging again. It is a permanent solution.  The challenge is to match exactly the existing glass shape, which they are very good at doing. Initially there may be some slight wind noise as the new glass settles into position in the frame however that soon disappears and the replacement is "as good or better” than the original. 

Conclusion

All in all, two very good ways to correct an ongoing problem in RVs. Talking with the experts, it would seem that if the window manufacturers used a better quality seal initially, the issue would be greatly diminished. We noted every brand and type of RV, trailers as well as motorized coaches, and several notable brands of windows, all were fogging and requiring repair or replacement. It seems to me that RVers need to raise the issue with the RV makers since most of these repairs are required after the RV makers warranty expires. RVers are footing the bill for what ultimately is a poor quality part. Perhaps it is time for RVers to question the RV makers about this issue. It will not go away unless changes are made. It seems that a simple improvement in the seal around the window would greatly reduce the problem. So there you have a review of two methods to solve the "fogging RV window problem”. Which you choose is up to you. The results will definitely provide you with many years of RVing satisfaction.