ANSI Z26.1 is the foundational safety glazing standard for motor vehicles in the United States. It defines the classification system used across automotive, transit, heavy equipment, and off-road vehicle glazing. Engineers who specify polycarbonate glazing for any vehicle platform need to understand it, because the AS designation on a material certification is a shorthand for a specific set of test results, and knowing what tests are behind that designation determines whether the specification is right for the application.
This guide explains the standard’s structure, the tests that matter for polycarbonate, and how to read a certification marking.
What ANSI Z26.1 Is and Where It Applies
ANSI/SAE Z26.1 (American National Standard for Safety Glazing Materials for Glazing Motor Vehicles and Motor Vehicle Equipment Operating on Land Highways) is published jointly by the American National Standards Institute and SAE International. The current version is ANSI/SAE Z26.1-1996, which remains the active reference incorporated by federal regulation.
The standard is incorporated by reference into FMVSS No. 205[1], the federal motor vehicle safety standard that governs glazing materials in all vehicles sold in the United States. This means ANSI Z26.1 is not optional guidance: when FMVSS 205 requires AS1 glazing in the windshield position, it is requiring compliance with the specific tests and thresholds defined in ANSI Z26.1 for the AS1 classification.
The standard covers glazing in passenger cars, multipurpose passenger vehicles, trucks, buses, trailers, and motorcycles. Heavy equipment, agricultural equipment, and off-road vehicles are not covered by FMVSS 205 directly, but their manufacturers commonly specify Z26.1 classifications as the technical benchmark because no equivalent off-road glazing standard exists at comparable specificity.
The AS Classification System
ANSI/SAE Z26.1-1996 defines glazing types numbered AS1 through AS12. Each type specifies which tests a material must pass and what the passing thresholds are. A material certified to a given AS class has been tested and confirmed to meet all of those requirements.
AS1: The highest classification. Covers windshields. Requires light transmission of 70% or greater, minimum optical distortion (evaluated by double-image test and refraction), penetration resistance under high-velocity impact, and head-form impact resistance. AS1 is the required classification for laminated safety glass windshields in passenger cars, trucks, and buses under FMVSS 205.
AS2: Covers side and rear window positions requiring 70% or greater light transmission. Impact and abrasion requirements are lower than AS1. Used for driver- and operator-adjacent windows where clear outward visibility is required.
AS3: Covers glazing positions where light transmission below 70% is acceptable. Typically applies to rear corner windows, supplemental glazing, and positions outside primary vision zones.
AS4 through AS9 cover specialized glazing types: rigid and flexible plastics for motorcycle and open-vehicle use (AS4, AS8, AS9), tempered safety glass (AS5), zone-toughened safety glass (AS6), and glass-plastic composite glazing (AS7). These classifications appear in FMVSS 205 position-approval tables for specific vehicle types but are less frequently encountered in polycarbonate OEM specification work.
AS10: Safety plastic (polycarbonate) for non-windshield positions where no minimum light transmission is required. Used for positions outside the primary visibility zone.
AS11: Safety plastic for non-windshield positions requiring 70% or greater light transmission. Covers side window positions for transit vehicles, heavy equipment, and trucks where polycarbonate replaces glass.
AS12: Safety plastic that meets windshield-equivalent requirements. The highest plastic classification. Requires 70% light transmission, optical quality equivalent to AS1, and full penetration resistance testing.
The Tests That Matter for Polycarbonate
ANSI Z26.1 contains a series of numbered tests covering optical, impact, abrasion, and chemical properties. Not all apply to every glazing type. For polycarbonate (AS10, AS11, and AS12), the tests with the most specification consequence are:
Test 8, Light Transmission: Measures luminous transmittance using a hazemeter or spectrophotometer across the visible spectrum. The 70% threshold applies to AS1, AS2, AS11, and AS12. The baseline methodology aligns with ASTM D1003[2]. Polycarbonate in the 3-10mm thickness range typically measures 88-90% without coatings. Coatings and tints can reduce this; verify transmission on the finished, coated part, not the raw substrate.
Test 17, Abrasion Resistance: Uses a Taber abraser with CS-10F wheels at 500 grams load for 100 cycles. Measures haze increase after abrasion. Uncoated polycarbonate fails this test. Hard-coated polycarbonate passes when the coating is correctly formulated and applied. This test is the primary driver behind coating requirements for polycarbonate glazing. ASTM D1044 uses comparable methodology and is commonly referenced alongside Test 17 in supplier specifications.
Optical Distortion: Evaluates image-forming quality by measuring double-image separation through the glazing. Strict limits apply to AS1 and AS12 (windshield-class) glazing. For AS11 side window positions, the requirements are less stringent. Polycarbonate produced with consistent thickness and uniform forming temperature generally passes, but panels with significant forming-induced stress or thickness variation can fail.
Test 20, Chemical Resistance: Tests resistance to specified chemical reagents including cleaning agents, windshield washer fluid, and common solvents. Specimens are evaluated for hazing, crazing, and delamination after contact. Coating compatibility with site-specific cleaning agents must be validated separately from the Z26.1 test, which uses standardized reagents rather than the full range of commercial cleaning products in use.
High-Penetration Resistance (AS12 only): Evaluates resistance to penetration by a steel ball impact of specified mass and velocity. Applies to windshield-class plastic (AS12). This requirement is why AS12 certification for polycarbonate requires significantly greater thickness than AS11, and why the base material and coating system must be tested as a composite assembly, not individually.
How to Read a Z26.1 Certification Marking
Certified glazing is required to be marked at the edge or in a corner with: the AS class designation, the manufacturer’s name or trademark, and a DOT (Department of Transportation) compliance code. A marking of “AS11 DOT-[code] MANUFACTURER” means the material has been tested and certified to the AS11 requirement set by a recognized testing laboratory, and it is approved for side window positions requiring 70% or greater light transmission.
The marking applies to the specific material and coating combination tested, not to the substrate alone. If a supplier changes the coating chemistry, thickness, or manufacturing process, the certification does not automatically transfer. Request documentation that the certification covers the specific grade, thickness, and coating being purchased.
Common Specification Mistakes
Specifying AS2 when AS11 is the correct classification. AS2 is a glass-based classification. The correct designation for polycarbonate in an equivalent position is AS11. A polycarbonate supplier certifying to “AS2” is either using incorrect shorthand or the certification is not valid.
Testing the substrate and the coating separately. Z26.1 tests the finished glazing assembly. A base material that passes Test 17 uncoated does not exist: uncoated polycarbonate fails. A coating that is tested on a flat substrate may perform differently when applied to a formed panel with edge stress. Specify and test the full assembly.
Assuming any hard coat passes Test 17. Different coating grades have different abrasion performance. Request haze-after-abrasion data for 100 Taber cycles at 500g on the specific coating and thickness combination, not a general product data sheet value.
Ignoring the light transmission measurement point. ANSI Z26.1 requires measurement at specific locations on the glazing. A panel that measures 72% at the center may measure below 70% at edges or in areas with higher forming-induced optical changes. Confirm measurements at the specified test locations, not just the nominal area.
Five Star’s Capabilities in the Context of ANSI Z26.1
Five Star Fabricating produces AS11-certifiable polycarbonate glazing for vehicle and equipment manufacturers. Fusionite coating grades[3] are formulated to pass ANSI Z26.1 Test 17 abrasion requirements. Light transmission is tested per ASTM D1003 on each production run. Chemical resistance data for specific cleaning agent exposure profiles is available on request.
Five Star’s lab testing capabilities[4] include the primary Z26.1-relevant tests: light transmission and haze (ASTM D1003), Taber abrasion (ASTM D1044), chemical resistance (ASTM D1308), and impact testing (ISO 6603-2, SAE J1615, FMVSS 205 S5.3). Five Star’s engineering and design team supports glazing specification development from geometry through production validation, with prototype lead times of two weeks from DXF or STEP file.
Contact
To request AS11 certification documentation, coating test data, or support with glazing specifications for a specific vehicle platform, contact Five Star Fabricating in Twin Lakes, WI: +1 (262) 877-2171.
View polycarbonate coating grades and glazing capabilities at fivestarfabricating.com/products-solutions/coatings-group.