What does a NAFS performance grade on a window label mean

Direct answer

A NAFS performance grade combines the performance class with a design pressure rating and a tested size. [1]

What the sources establish

• A NAFS performance grade combines the performance class with a design pressure rating and a tested size. (NAFS 101/I.S.2/A440) Applies to: Interpretation of a NAFS performance grade. Does not apply to: Products quoted with a design pressure but no tested size or class. [1]
• A NAFS product label or certification report identifies the product designation, performance class, performance grade and tested size. (NAFS 101/I.S.2/A440) Applies to: NAFS product labelling and certification reports. [1]
• NAFS assigns performance classes — R, LC, CW and AW — that indicate the intended application and performance level of a fenestration product. (NAFS 101/I.S.2/A440) Applies to: NAFS performance class designations. [1]
• NAFS establishes performance requirements and test methods for windows, doors and skylights, including structural, water penetration resistance and air leakage performance. (NAFS 101/I.S.2/A440) Applies to: Window, door and skylight product performance. [1]

Orange County context

Orange County homeowners are governed by the California Building Standards Code as adopted statewide, applied locally by each city's building division. The requirements above are drawn from the Current published edition edition(s) cited in the source list. Most of Orange County falls in California climate zone 6, with inland areas in zone 8, so the applicable fenestration values depend on the zone of the project address.

This page explains published requirements. It is not a plan check, and it does not replace confirmation from the building division with jurisdiction over your address.

Related reading

• How to Verify a Window Contractor's License in California
• Low-E Coatings, Argon Fill and Spacers: How Window Glass Performance Works
• Replacement Window Cost Breakdown in Orange County

Every factual statement above is traceable to a recorded fact, a cited source, the source edition and the cited section, listed in Sources & Citations below.