Can window insulation cause damage to your RV windows?

R & T De Maris photo

With summer just around the corner in some spots around the U.S. (and already here in others), RVers are beginning to concern themselves with coping with the heat. In these writers' corner of the world, Quartzsite, Arizona, the local hardware store sells yards and yards of Reflectix – an insulating film that reminds us of a layer of bubble wrap plastic sandwiched between two layers of aluminum foil. Many locals buy the stuff and stick it up against the insider of their windows to keep old Sol from beaming in and heating up the house.

However, one of our sharp-eyed and concerned readers recently dropped us an e-mail, expressing concerns about possible damage this could cause. "I think I recall reading that some window seals can be damaged by this heat," reads the missive. "It may also be the case that condensation can develop between the material and the windows which may also cause damage in some circumstances."

We followed up our reader's concern by first contacting Reflectix and asking their opinion. A company representative told us, "We do not recommend the use of Reflectix in windows." Uh huh. But why? The concern is that incoming heat may not be able to adequately escape the space between the insulation material and the window itself, which, in the company opinion, could cause, "the window to crack or bow."

Since we've seen plenty of RVers install Reflectix or similar materials in their rigs and yet not having heard of any problems, we probed a bit deeper. This time, 'the horse's mouth' that we called on for a second opinion was RV manufacturer, Dutchmen, in Goshen, Indiana. The company representative here told us that putting Reflectix in an RV window, "is not something that will harm the windows unless they are dual pane widows." Ah! There's the catch! Single glazed windows don't seem to have a problem, but the folks at Dutchmen warn that dual glazed glass can overheat, and possibly end up leaking.

Over the years we've owned a lot of RVs, and none of them ever had dual glazed windows – maybe why that's why we've "gotten away" with using insulated material in ours. So, check your situation out. Got single pane windows in your rig, you're probably OK using Reflectix. Dual glazed windows? Use Reflectix at your own risk.