Psychology: Sheltered Sanctuaries
By Judy Penz Sheluk
No area of the home building industry is more prone to problems than window installation. Since the era of leaky condos in British Columbia brought the issue to the forefront, manufacturers, installers and researchers have been searching for solutions.
|CSA A440 water test performed at the Vinyl Window Designs lab.|
Among the groups trying to improve the situation is the Siding and Window Dealers Association of Canada. About eight years ago, SAWDAC established Window Wise, a quality assurance program aimed at giving homeowners the assurance that they were buying a quality window and that the window would be installed by a certified installer.
David Mitten, SAWDAC's executive director, says the program audits and certifies contractors and window manufacturers, and conducts comprehensive training seminars for installers.
The Window Wise program is aimed at homeowners who want the security of knowing they have purchased a quality product from a qualified installer. Mitten says that, while there are hundreds of window manufacturers in Canada, only 17 are Window Wise approved. One reason for the low number of manufacturers in the program is that all Window Wise windows need to meet the Energy Star criteria. That, of course, makes the window more expensive.
Contractor members must also meet SAWDAC's stringent criteria, which require that a company has been in business for three years and has a good reputation. Reputation is checked through credit reports and supplier references.
Under the program, contractors are trained in proper installation techniques. A Window Wise installation specifies more than 25 criteria for a quality, energy-efficient installation. When installation is complete, the jobs are registered and inspected on an ongoing basis. Along with the registration, the homeowner gets a five-year Window Wise guarantee that backs up the guarantee offered by the manufacturer and contractor.
While the program has met with good success in Ontario, where a large number of contractors are certified, it has had limited success in other parts of the country. "We definitely want to get more contractors," says Mitten. This year, SAWDAC is planning a push to beef up the program's presence in Quebec and Alberta.
SAWDAC also conduct seminars aimed at giving the membership the latest information on best practices with regard to installation. At a recent seminar, the association brought in Silvio Plescia, a senior researcher in the Technical Research Division of CMHC.
"Contrary to popular belief, the airtightness detail of a window should be on the inside edge… not the outside."
Silvio Plescia, Technical Research Division, CMHC
A scientific look at
the installation process
A building envelope expert, Plescia has spent several years studying issues related to window installation and window performance, especially the performance of the interface between the window and the wall assembly.
One problem that has constantly bedevilled both installers and researchers are details, and what constitutes good details in window installation. Everyone seems to have a different take on what are good details, says Plescia, and every builder or crew does things in a slightly different way depending on what materials are present or not present. Since no one really knows which details work and which don't, the National Research Council and CMHC are currently conducting a study testing a number of different installation scenarios.
Details are tested under pristine conditions and then deficiencies are introduced into the system to see both where and how much more water gets into the wall. Through the tests, researchers are learning how much water gets into the assembly and how it gets from one location to another.
The tests have been going on for about a year and a half and the first phase is coming to a conclusion. A report is expected sometime this spring. In the meantime, CMCH and NRC are disseminating the information through seminars. They started in November with a seminar at the Buildex Show in Calgary. Another was held at the Construct Canada Show held in Toronto last December. Regional seminars are also being sponsored by the Canadian Window and Door Manufacturers Association (CWDMA).
Plescia says he tries to break the seminars down into three key points. The first is to protect the sub-sill using some type of impermeable membrane. "All our field tests have shown that water does get down there so sub-sill protection is imperative."
windows tighter on the Inside
Our tests have found that, contrary to popular belief, the airtightness detail of a window or connection to the air barrier system of the house should be on the inside edge where the window connects to the inside wall of the house, not the front or outside edge of the window where the window connects to the exterior sheathing of the house.
Most current strategies want the installer to make the outside connection, where the flange of the window connects to the sheathing system of the house, as tight as possible. The thinking is if they tape and seal the outside edge and flange area of the window they'll stop water from getting into the assembly.
In fact, tests have shown that the opposite is true, the reason is air pressure.
Plescia says, "Our tests have shown that even under low-pressure conditions water does get in. It creates funnels and gaps and openings because you have a high pressure drop at the same location where you have water. Because of that high pressure drop, you are actually encouraging water to be driven through. There are high pressures and water is being driven through deficiencies in the system." That happens, says Plescia, no matter how the details are done.
The tests showed that, under conditions where the window's connection to the outside sheathing of the house is made looser and the seal to the house's air barrier system is at the back, where the window connects to the inside walls of the house, some water does get in but not nearly as much as in the previous condition. The pressure caused by the airtight seal, it turns out, is actually drawing the water in, rather than allowing it to drain away.
Plescia says that loosening the front or outside connection of the window actually helps to solve the problem. While it allows some water to get in, proper sill protection will allow the water to be collected and drained away in an effective manner that is less damaging.
His third and final piece of advice to installers is to ensure that materials are properly ship lapped, especially with flanged windows which make up the bulk of windows used in new construction. Membranes should come over top of the flange at the head and underneath at the sill for the window to shed water properly.
Updating the CSA 440
The Canadian Standards Association is also working on the problem of window installation. For the past three years a committee made up of manufacturers, associations, engineers and consultants from all regions of the country has been working to create a new version of CSA 440.4 that is aimed at creating a new standard for window installation.
Committee member Phil Lewin, VP of Marketing at Vinyl Window Designs in Woodbridge, Ontario, says the biggest problem has been to create one standard that will be acceptable in all regions of the country and one that is suitable for new construction and renovation. "There is no one answer that makes everybody happy," Lewin says.
Given the geographic differences, Lewin says the new standard has become "a very thick document." That worries a number of people who fear that if the standard is too complicated, it won't be adapted and followed in the field.
"The goal," he says, "is to put out good information, some of which may be ahead of its time, but is valid and well thought out in regard to issues of regionalization and different weather patterns. The hope is it will move the industry as a whole to correct some of the obvious mistakes that we presently have." And, while it may not be perfect, he says, "It is the standard that the best minds that could be assembled on the subject have put together."
The document is currently under review and, due to its complexity, Lewin is unable to say when it will finally be issued. HB