Although frame and glazing technologies have improved the design performance of today’s residential windows to achieve remarkable energy efficiencies, all that effort can go to waste with a poor installation.

In turn, an improper install can cause latent defects, including mold growth and rot that can impact the building’s overall performance and indoor air quality.

As much as builders may want to point the finger at suppliers, they first need to look in the mirror. “If installers simply paid attention to detail, it would solve 80 percent of the problems we see,” says Alan Mooney, P.E., president of Criterium Engineers in Portland, Maine, a building performance consultancy that annually inspects about 20,000 single- and multifamily homes across the country. “They have to think about how it’s all supposed to go together.”

The problem, he says, is that the current pool of construction labor, in general, lacks the skills, knowledge, and interest to analyze an installation—despite increasing efforts among window manufacturers to supply detailed instructions and often components that aid in the effort. “It amazes me that something so fundamental and straightforward as flashing, regardless of the material used, is installed exactly the reverse of how it needs to be.”

In addition to simply following logic and printed instructions, Mooney encourages builders to create mockups or models that show proper installations—a more common (and proven) practice in commercial construction—and leave it on site for ongoing training purposes. “Put the pieces together outside of the envelope first, and see if they work and catch problems before they impact the project,” he says of the mockup concept. “Photograph and videotape the way to do it, and show it to every installer who comes on your site.”

Mooney also sees signs that manufacturers may soon require (and provide training for) certified installers for their products and inspect installations before they’ll activate a product warranty. “If that can be effectively administered and monitored, that’ll be a good thing,” he says, for everyone along the window supply chain.—R.B.

Detail-Oriented: An improper installation can completely negate the qualities of high-performance windows.

Courtesy Pella Corporation

Learn more about markets featured in this article: Portland, ME.