Tom Shafer

5 myths about windows

August 17, 2016

You've been around windows your whole life. You see them every day. You may have even purchased your own at some point! You'd think that would make you an expert, but some of these common myths may have crept into your good, solid knowledge:

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Myth one: insulated glass is hermetically sealed

Hermetically means totally sealed against migration of gasses into a sealed unit. Insulated glass is a sealed unit, but it's not hermetically sealed. Gasses, in fact, do migrate into your insulated glass, and one of these gasses is air, which contains water vapor. That provides a key clue for how you know this one is a myth. Do you ever see condensation between the panes of your window glass? Then you know it isn't hermetically sealed.

Myth two: the space inside a double glass unit is a vacuum

This one is just wrong, plain and simple. When the window is manufactured, it's done in a room where the air is at an ambient pressure. When the window is installed in a home, the pressure in the unit slowly increases or decreases to match air pressure outside the unit. Plus, if it was a vacuum, the panes would touch since no pressure would separate them, and that's not what you want.

Myth three: vinyl clad windows rot quickly

Several things make this untrue. Firstly, the wood beneath the vinyl is treated with a preservative to prevent rot. Secondly, the vinyl covering is extruded totally around the wood, or if it is applied in pieces, is totally sealed to the wood. Which means, thirdly, water it sealed out, so the wood won't rot.

Myth four: aluminum clad windows dent

This one is only partly false. What we should say is that thin aluminum dents. Thin aluminum is usually roll formed, which means you're continuously bending a strip of metal, hence it must be rather soft and pliable. That same pliability means it lends itself to dents on impact. However, windows with heavier, thicker extruded aluminum are much more resistant to denting.

Myth five: low-e glass is tinted very dark

For reference here, clear glass has 79% visual transmittance. A good quality low-e glass that meets Energy Star standards has a visual transmission of .69, or a 31% decrease in darkness. However, this is barely discernible to the human eye. To make a comparison, a car windshield has a visual transmittance of 35%

And now you know! Before you decide against buying windows because of something you've heard about them, do some research first. It might just be another myth.

About the Author

Tom Shafer has decades of experience in window sales, marketing and product development. He's worked closely with window design engineers in testing, design, and building code interpretation. Past employers include United Windows and Doors and Norandex, MI Windows. He currently works at a home improvement retailer.


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