Clearing the Fog

Motorhome Window Replacement
Photos by Bruce W. Smith

Laminated glass is a practical solution for fixing clouded dual-pane windows that impair drivers’ vision from the cockpit

A cataract, defined as the clouding of the lense in the eye, is one of the leading causes of blindness in the world, and is a common malady among those older than 40 years of age. Aging has a similar effect on the dual-pane windows in motorhomes, causing a white fog to slowly build up between the glass to the point where the only view is one of looking through a white cloud.

Fogged windows along the sides and rear of a motorhome are a nuisance that can be tolerated until it interferes with the vision of the driver and becomes a serious safety issue.
This malady is more prevalent in older motorhomes that have been exposed for a long time to sun and/or have a broken seal. All dual-pane windows are subject to the same problem.
RV Glass Solutions in Coburg, Oregon, specializes in rectifying dual-pane motorhome windows that have failed. According to the company, fogging isn’t caused by the age of the RV, but rather the failure of the parts between the window panes. Either the desiccant-filled rubber spacer between the two panes of tempered glass – which is what absorbs moisture being pulled into the air space from changes in temperature and elevation – becomes over-saturated, or the secondary sealer on the outside of that rubber spacer fails from all the vibration and movement of the motorhome, allowing moisture to saturate the spacer and work its way into the air gap.

Regardless of which part quits doing its job first, moisture builds up on the glass pane’s interior surfaces, resulting in the fogging effect. If left unchecked for a long enough period of time, the calcium deposits left by the water vapor will eventually etch the glass, rendering it unrepairable and permanently clouded over.

Multiple Solutions

Fortunately, there are several solutions for restoring clear vision. The compromised window assembly can be removed in its entirety and replaced if the original window manufacturer is still in business – and is still making the assembly. It’s also the most expensive option, with three-piece units likely costing more than $1,000.

A much better alternative is to remove the window assembly, then completely disassemble it so the individual panes of tempered glass can be cleaned (or replaced if they are etched) and resealed using new desiccant-embedded rubber spacers coated with the secondary external sealer. Cleaning and resealing of the OE tempered dual-pane glass is one of RV Glass Solutions’ specialties, and the company uses a proprietary process which it keeps close to the vest, so it wouldn’t let us show readers the secrets to its success.

The downside is, like all dual-pane RV windows, no matter how successful the glass cleaning/replacement/resealing process is, the same fogging issue may rear its ugly head again. (RV Glass Solutions provides a two-year warranty on its dual-pane repairs.)
A third alternative, the one many motorhome owners choose, is to replace the dual-pane windows with a single piece of thick, laminated glass. The laminated glass RV Glass Solutions uses is the same found in the automotive industry, where a thin layer of either polyvinyl butyral (PVB) or ethylene-vinyl acetate (EVA) is sandwiched between two thicker sheets of glass bonded together by heat under high pressure to form one single piece.
Laminated safety glass has several advantages over dual-pane glass, according to the company, one of which is it doesn’t shatter when broken because the plastic interlayer holds it together, adding a level of safety and security in the event of an accident or vandalism. The major downside to using laminated glass is the loss of the insulation factor provided by the dual-pane windows, which will limit the effectiveness of the windows in hot and cold weather. According to Colorado Energy, single glass, including a laminated window without an air gap, has an R-value of .91, whereas a dual-pane window with a ¼-inch air gap has an R-value of 1.69.

But the primary reason to ditch dual-pane glass for laminated is it will never fog. Hence, the reason RV Glass Solutions gives a lifetime warranty to the original owner when it replaces OEM dual-pane windows with laminated glass.

Cost Factors

The cost for either repairing non-flush-mounted windows with tempered OEM dual-pane, or replacing them with laminated glass, varies from installer to installer. At RV Glass Solutions, which is under the corporate umbrella of Coach Glass, one of the major suppliers of windshields to a number of motorhome builders, pricing for such work is very simple: $325 for a single-window assembly; $430 for assemblies with two windows; and $535 for units that have three windows.

The company has a vast reference file of RV window drawings and specifications to program computerized glass cutting machines on-site to ensure each piece is a perfect fit. It also has an abundant supply of laminated glass sheets on-site in auto green, light gray, dark gray and bronze tints, which covers 90 percent of the RV market, according to RV Glass Solutions.

Pricing on replacing damaged (etched) OE tempered dual-pane glass with like glass is more complicated. New tempered glass prices vary widely depending on a number of factors, including pricing differences in thickness and color. Sometimes the price is nearly the same as using laminated glass, sometimes it can be considerably higher. It all depends on the installer’s glass cost.

Making Time

From a time standpoint, repairing or replacing RV window glass takes about the same amount of labor regardless of the type of glass used. RV Glass Solutions says it takes a tech about three hours to R&R one of the larger multi-window units such as the three-pane “pilot window” commonly found in motorhome cockpits, and each of the techs can typically make two or three of those types of window repair/replacements a day at the massive Coburg facility.

Smaller single- and dual-pane windows take less time. Most of the motorhomes that come to RV Glass Solutions’ service centers (located in Oregon, Arizona, Florida and Indiana) are by appointment. They do accept drop-ins during the slower times of the year, but recommend making an appointment, especially during summer.

The payoff is obvious after the driver slides behind the wheel and can see clearly through the side windows – much the same as when vision is restored after cataracts are removed.

RV Glass Solutions | 888-777-6778 |



  1. I have a 2004 freight liner explorer 38N. I like Your article as it Niels points of the foggy window specially driver side with that I was wondering if you could give me a quote for a three-piece unit for the vehicle described above I can always send you the VIN number if needed I have a diesel mechanic out this way so we would be able to take the window out should be able to install? If you could send me a quote that would be great I’m sure shipping will be an added cost thank you for your time and look forward to your response

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