We are currently working on a window replacement project at the United Arab Emirates building in Washington D.C. Built in 1912 in the Beaux-Arts style, the embassy is part of the former grounds of the National Bureau of Standards in Cleveland Park that became a high-security enclave just outside of Embassy Row. This enclave houses 18 embassies in historic buildings from the late 18th Century through the early 20th Century in an eclectic mix of Queen Anne, Georgian Revival, Tudor Revival, Beaux-Arts, and other styles.
For this project, our windows were required to undergo testing procedures we haven’t gone through before. We found the experience so interesting that we’re highlighting the results here. (Don’t worry – we’ll highlight our work on the building in a future newsletter, and we’ll post about the Beaux-Arts style in another post.)
First, the results…
This was my first time experiencing the testing process and the whole thing was really interesting to me. They force the product through conditions I have never experienced in “real life” (which makes me wonder exactly what situations they are making the windows qualify for?).
Our fixed window surpassed all the testing and actually withstood F5 hurricane forces!! (And yes, we were there to witness those forces… behind safety glass of course.)
Our single-hung window performed well enough to earn the rating we “had” to achieve, but they stopped the testing at that point and did not push it to the limits like they did with the fixed sash because the window (understandably) did experience water infiltration at one point. (Hey, it opens, so it’s got moving parts – you kinda have to expect iit. Especially when there is a wall of sprinkler heads spraying water on it from every direction.)
Since you can only get a rating as good as the lowest test, they stopped the other tests when they passed the point they needed to for the rating we were required to have. It was kind of disappointing.
I would have liked to have seen the single-hung pushed to its limits as well. But we construct them the same waY as the fixed sash, so I would assume the single-hung would have performed as well on the structural tests as the fixed sash if they had.
Danielle was feeling under the weather that day, sick and surely contagious. But none of us could convince her to stay home, so we headed out to the National Certified Testing Laboratories in York, PA. (Hoping we weren’t setting a pandemic in motion with her germs.)
Two windows were going to be tested for air leakage, water leakage, and how much air pressure they could withstand structurally. To test the windows, they clamped them to a large plexi-glass wall. This structure was surrounded by a plastic box that was taped at the seams to eliminate any outside air flow from impacting the tests.
For the air leakage, forced air was directed at the window to measure how much air leaked through the window to the other side. When they tested the damp-water penetration resistance mechanical spraying devices sprayed water at the windows in 5-minute cycles, with one minute between cycles for the wood to rest, that increased in pressure with each cycle until the window reached its fail point and water would fall over the lip of the sash. During this test the window was constantly monitored by a testing technician who viewed the window from the back side of the testing wall where he visually inspected the joints for water penetration during the testing with a flashlight.
The last test was the structural load test and this was definitely my favorite. Sensors were applies to various points on the sash to measure movement. Both positive and negative pressure were increased substantially in cycles. This test was simulating the kind of forces a window would experience during a hurricane and as the pressures were increased in each cycle you could visibly see the bowing of the window. As it neared its fail point you could hear the cracking of the wood.