First, NAFS’ mandatory testing protocols involve measuring air leakage as per ASTM E283-04 at 75 Pa (1.57 psf). The result will be a measure of the volume of air going through the window at stable pressure differential per second and divided by the window surface area. Fixed products must meet the fixed level air leakage requirement of 0.2L/(s•m²) [0.04 cfm/sf], and operable products must minimally comply with the A2 level requirements of 1.5L/(s•m²) [0.30 cfm/sf]. The expression “air leakage” is used because both infiltration and exfiltration are tested since air can flow in both directions (refer to Sidebar 3 below).
Next, resistance to water penetration, validated in NAFS, follows ASTM E331-00 uniform static air pressure. Depending on the PC, the window specimen must resist water leakage at a defined minimal pressure of 15 per cent of the design pressure. Criteria to succeed this test differs in the U.S. and Canada. Be cautious when analyzing products to ensure the water penetration test complies with Canadian test requirements, namely that no water remains in an undrained fenestration framing cavity. However, water retained as droplets or surface film are not considered evidence of a failed test.
Finally, structural testing for NAFS references ASTM E330/330M-14, which involves two types of tests, each at a positive and negative static load.
- The first test validates how much a window will deflect under a specified design pressure. This does not validate for dangerous wind loads conditions, but it can demonstrate highly uncomfortable window movement for taller specimens. While all PCs are required to test for structural deflection, passing L/175 is only mandatory for commercial window (CW) and architectural window (AW) classes.
- The second tests the structural-ultimate wind load to 150 per cent of the static design load. All PCs must pass successfully to comply with NAFS. Operable products must remain locked during the test and operate after the test’s completion. This test helps ensure occupants egress safely.
| Sidebar 3 – Air leakage requirements in codes |
| • Give special attention to fenestration products’ air leakage requirements. The National Building Code of Canada (NBC) 2020 and the National Energy Code of Canada for Buildings 2020 (NECB) do not have the same requirements for operable windows. • Fixed windows and Other Fenestration Assemblies must meet 0.2L/(s•m²) [0.04 cfm/sf] in both the NBC 2020 and NECB 2020. • For operable fenestration products, the requirement is 1.5 L/(s•m²) [0.30 cfm/sf] in the 2020 NBC, and 0.5 L/(s•m²) [0.10 cfm/sf] in the 2020 NECB. Remember, when a building is within the scope of a NECB, performances required in the NECB take precedence over those in the NBC. |
In addition to these essential test protocols, NAFS describes minimal requirements to ensure products are easy to use, their screens remain in place on windy days, and they resist forced entry. This forced-entry test does not consider glass breakage type, but the product’s resistance to a quieter and less noticeable intrusion with the help of tools.
Products from all PC must also undergo the minimal mandatory tests. Their differences lie in the minimal dimensions of the tested samples, and the minimal water and wind load pressure they must meet. CW and AW classes are required to not exceed L/175 during the structural-deflection test. R and LC classes are tested to this, but the result does not determine a pass or fail.
