Window performance standards define window products by Performance Class (residential, light commercial, commercial, heavy commercial, and architectural) and Performance Grade (15, 20, 25, etc.).

Local building codes likely define the minimum Performance Grade. In general, R and LC class windows have smaller test sizes. They also are allowed less force to operate and lock. But in many cases they offer size, design wind pressures, water resistance, air leakage resistance, forced entry resistance, and hardware performance associated with the C, HC, and AW classes.

The Performance Grade is based on the design wind pressure, calculated from the building code, as noted previously. If the maximum design wind pressure is 25 pounds per square foot, then the Performance Grade needs to be 25 or greater. Performance Grade is designated by a number following the product type and class designation.

FAQ’S

Q: How are Performance Class and Performance Grade determined for window products?

A: Performance Class and Performance Grade for window products are determined based on established window performance standards. These standards categorize window products into different classes such as residential, light commercial, commercial, heavy commercial, and architectural, each with varying performance requirements. Performance Grade, on the other hand, is a numerical designation (e.g., 15, 20, 25, etc.) that indicates the window’s ability to withstand design wind pressure, calculated according to building codes.

Q: What factors influence the assignment of Performance Grade to different window classes?

A: The assignment of Performance Grade to different window classes is influenced by several factors. These include the intended use of the windows (residential vs. commercial), the size of the windows and the required level of force for operation and locking. Performance metrics are also factors such as design wind pressures, water resistance, air leakage resistance, forced entry resistance, and hardware performance. Generally, R and LC class windows may have smaller test sizes and lower force requirements compared to C, HC, and AW classes. But they must still meet specific performance criteria associated with their designated Performance Grade.

Q: Are there any specific regulations or standards that dictate the relationship between Performance Grade and Performance Class for window products?

A: The relationship between Performance Grade and Performance Class for window products is often regulated by local building codes, which typically specify the minimum Performance Grade required for different classes of windows. These building codes ensure that windows installed in various settings meet the necessary performance standards to withstand environmental factors such as wind pressure. However, the specific regulations or standards governing this relationship may vary depending on location and jurisdiction.