Window testing: Ultimate quality control
A little known but fundamental part of the window, curtainwall and building facade industry is the testing of these products in laboratories and also in the field. The purpose of testing windows, curtainwalls and building facades is to ensure that the products will perform as intended, and if not, to find out why.
Types of window testing
1. Window testing for certification
These window tests are performed in a laboratory on standard sized window products, usually individually, to allow a product to achieve a certain “class” or performance category. An example of this would be, according to AAMA/WDMA/CSA 101/I.S.2/A440-11, NAFS — North American Fenestration Standard / Specification for windows, doors, and skylights, a window product being certified as a AW-PG40-AP projected window would need to pass an air test at 6.27 psf with an allowable of .10 cfm/sf. then pass a water test for 15 minutes at a test pressure of 8.15 psf, a structural test at 40 psf with maximum deflection of L/175, then pass a whole slew of other tests. When the window product meets all of these test requirements, it can then be labeled as a AW-PG40-AP, which tells the consuming public that such performance has been achieved.
2. Field test of windows and curtainwalls
On larger projects it can be valuable to perform the same certification test that was passed in the laboratory, in the field where additional factors have affected the window performance such as handling of the product, installation, condition of the surround and condition of the field applied sealants.
In field window tests, usually only air and water tests are performed in the field, but I have seen a structural test on a curtainwall in the field. Some specifications allow lesser performance in the field than in the laboratory. Sometimes field air tests will have the allowable air infiltration 1.5 times the laboratory allowable. Water tests can be discounted in the field by reducing the test pressure, sometimes by a factor of 2/3.
It is important that the architect specify laboratory as well as field window test performance in order to avoid unnecessary conflict at testing time. This will be a sticking point!
3. Diagnostic window testing
This is window testing performed because something has gone wrong, such as window air or water leaks. In many cases the window testing starts with a reasonable variation of the certification test as a starting point, then other methods are employed to isolate individual parts of the window system to determine exact points of entry. Curtainwalls can also be tested using diagnostic methods.
Diagnostic window testing is an art form requiring a highly experienced test technician because creativity must be sometime used to find the leak. Yet the improvised test should be within reasonable constraints so that the diagnostic window test is not unduly in excess of the project performance criteria.
4. Visual mockup of windows and curtainwalls
This type of mockup is often built on site in advance of the actual construction in order to give the architect and other stakeholders a visual representation of how the window, curtainwall or skylight material will look. It can be effectively used as a standard for visual acceptability as the job progresses. One of my clients, an architect with a university client in New York is using a visual mockup to generate student interest and to attract donor contributions.
5. Pre-construction mockup testing of windows and curtainwalls
This is the mother of all testing and my personal favorite because you get the opportunity to build and test an entire section of the building in a lab where the bugs can be worked out without creating a big problem in the field. Pre-construction mockup testing is a mini-version of the actual project. It has all the elements of a full-fledged construction project including separate drawing submission, separate material order, worker mobilization at the lab. It involves actual assembly and installation of windows, curtainwalls, panels, and possibly even stone or masonry to simulate a part of the actual building. Usually there is an elaborate window test procedure that was initially presented by the architect in the bid specifications, along with a definition of the area to be built and tested in the lab.
Continue to Part 2:
Preconstruction Mockup Testing: A Guide for Construction Professionals
More about testing of window and curtainwalls
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