This test is performed at a test pressure that represents a 40 km/h wind. The window leakage is measured in cubic metres per hour per metre of crack length, which is the length of opening joint between the sash and the frame. A1 is the maximum leakage that is allowed with the A2 and A3 levels being 60% and 20% of the A1 maximum respectively. Even a fixed window may have some air leakage and it is allowed at 10% of the A1 leakage level.
Water Tightness (or Water Leakage) Test
The water leakage test is performed by spraying the window with a constant stream of water, raising the test pressures to simulate increasing wind loads, and observing if any water gets inside the window. Each level (B1 to B7) represents wind load starting at 57 km/h (B1) and rising incrementally to 123 km/h (B7). Because different parts of Canada have different wind loads and these have been measured and published, the National Building Code requires different minimum levels for windows in different regions.
Wind Load Resistance Test
This test measures the deflection of the window components under increasing pressures, which represent higher wind loads. There is also a test to see how the window withstands hurricane force winds. The number in the chart indicates wind speeds measured in km/h. The range for this test is C1 to C5.
