Fenestration Review

Philibuster: Testing and standards in fenestration have changed so much since the ’80s

October 13, 2022  By Phil Lewin

Let’s take a trip to the dark ages of the window industry. We can start with my very first attendance at a Canadian Window and Door Association (now Fenestration Canada) convention in the ‘80s. When an experienced participant discovered that I was new, he joyfully took this as an opportunity to tell me the industry’s history.

Do you know why a basic replacement window in North America has a depth of 3.25 inches? At one point Andersen Windows accounted for as much as 40 percent of all windows sold in the U.S. and 3.25-inches is the distance between the two blind-stops in a double-hung Andersen window. So, you would remove a blind stop, cut the ropes of the balance, place the new replacement window inside the frame and replace the blind stop. Yes, eventually some installers used some fibreglass insulation and shims.  

My teacher had just about caught up with window technology by ending emphatically with the statement that another gentleman had “saved the industry” by inventing semi-sashless sliders when the sashless sliders that compressed two pieces of glass against each other were outlawed by code. I tell you, this gives context to the state of the industry.

Many CWDMA meetings later, when the industry was actually making progress toward more efficient windows, I attended another presentation by the luminaries from the National Research Centre.


Clandestine agents of the NRC had purchased a group of sample windows from a variety of different material categories. The windows were off-the-shelf and acquired so that no one would suspect that the intent was to test them. This was in the pre-certification days and (would you believe?) there were rumours that the windows sent to test labs were full of quality modifications not used on production models! The purchased windows were all as close as possible to the actual test sizes in the new A440 and included common window styles in vinyl, wood, fibreglass and aluminum. 

The windows were put through the standard tests. Then, in a procedure still not done, the windows were put through simulated aging. Some of this included mechanically opening and closing the units to simulate long-term wear and putting the windows through heating and cooling cycles as an attempt to simulate the effects of usage over time. Then, the windows were put through the same series of A440 testing as before the simulated aging.

Vinyl window results for the initial test were somewhat lower than the published performance from the manufacturer. What a surprise. Post-aging was even lower, primarily due to wear on seals. An audience member noted that seals are replaceable. Wood windows also had lower initial performance results. In the post-aging testing, there were signs of deterioration of the wood, contributing to even lower test results. Fibreglass tested well initially, but after aging had a problem with water leaking through the frames. It was determined that the mechanical corners of window frames were not adequately sealed to resist the aging simulation. If I recall correctly, one fibreglass representative in the audience questioned the validity of the simulated aging procedures. I’m sure that those of you from companies that have installed fibreglass windows over the last few decades would have the best data on the validity of this issue. Aluminum was saved for last, probably so the presenters could end with a good punch line. The good news for aluminum was that the windows showed the same results before and after they were tested. The bad news was that in the initial testing, the aluminum windows failed to meet the lowest result level required to be used in Canada. 

I believe there were two points the presenters wanted to make. The first being that the testing system where manufacturers were on their honour to test and then produce windows as tested was a failure. This presentation initiated the ball rolling for the certification we have today. The second point was that how a window performed new was not an adequate measure of its long-term durability and some kind of simulated aging testing was justified. This has never been adequately addressed.

Phil Lewin is technical director for SAWDAC.

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