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Fenestration Forum: June 2013

I have learned from firsthand experience that in situ testing of
building enclosure systems often presents a number of technical and
logistical challenges.

I have learned from firsthand experience that in situ testing of building enclosure systems often presents a number of technical and logistical challenges.

I was initially exposed to on-site testing while inspecting fenestration installations for high-rise, non-profit buildings. There are cases when this testing may be problematic because of the wide range of environmental conditions that may exist on site, or from the less-than-ideal location of the area(s) selected for testing. Essentially, you are attempting to simulate a severe weather event, which can be difficult even in a controlled laboratory setting. Despite this, I feel in situ testing is a critical tool for quality control that should be deployed far more often than it is.

Manufacturers typically invest considerable resources in laboratory tests, but these test the products, not the installation. Wall systems have evolved over time and become more complex. In my view, they now require more attention to detail to install correctly and without defects. That being said, certain general installation principles will improve the chances of providing effective environmental control within acceptable limits. Contractors who follow these principles have little to fear from on-site testing of their work.

One principle involves paying close attention to the interconnection details between the fenestration product(s) and the water-resistant barrier in the wall system. These barriers need to be properly lapped if they are to perform as intended and failure to ensure continuity where these components interconnect can be a potential source of air or water leakage during the building’s service life.

Another installation principle (that applies mostly to designers) involves operating on the assumption that wall systems may experience water penetration at some point and ensuring there is a drainage path for moisture to escape. This drainage path may also serve to provide ventilation, which can allow the system to dry.

For installers, good building practice involves making sure that on-site conditions are suitable when using sealants and weatherstripping. This includes ensuring that surfaces are dry, clean and free from contaminants such as dust or construction debris. This can be difficult on construction sites.

Temperature may also be a factor in proper sealant application and contractors must pay attention to the manufacturer’s instructions.

It is also important that these sealants (or self-adhering flashings) are durable enough to withstand exposure to Canadian temperature extremes and UV radiation.  In our climate, the temperature extremes result in almost continuous expansion and contraction. It falls to the designer and specification writer to select products that can handle this kind of stress.

The cost of the building envelope in relation to the cost of the entire structure has gradually increased. This is due in part because of the complexity as well as the number of components and contractors involved. In fact, the cost of the enclosure system for newly constructed buildings can equal the cost of all the other building elements. As a result, effective quality control and testing cannot be overlooked or deferred. It is estimated that defects that may lead to moisture penetration or accumulation within the wall systems comprise a significant percentage of reported deficiencies. In my opinion, testing for these defects often does not receive adequate attention, in spite of the fact that we know how to apply quality control expertise to prevent them.

Developers, agencies, architects and other professionals involved with the construction sector all have a vested interest in ensuring adequate quality is achieved, and in keeping water on the outside.

Brian Burton is a business development consultant and is serving on the Personnel Committee for the CSA’s Certification Program for Fenestration Installation Technicians. His current interests include adaptive reuse of buildings, overcladding technologies, maintenance of the building envelope and the rapidly growing use of computers in construction. You can contact him at brianburton@live.ca or visit his new website at http://burtons-pen.com