UL 2218, ASTM D3161 and UL 790: What Do These Numbers Mean?

Roofing marketing is full of phrases like:

tested

proven

storm resistant

But tested for what?

Against what standard?

Three performance standards homeowners may encounter are:

• UL 2218
• ASTM D3161
• UL 790

GoNano publicly cites testing of its nanotechnology treatment under these standards.

UL 2218 — Impact Resistance

UL 2218 evaluates roofing resistance to impact.

Ratings range from:

Class 1 to Class 4

with Class 4 representing the highest classification in the standard.

This test is often discussed in relation to hail-impact performance.

ASTM D3161 — Wind Resistance

ASTM D3161 evaluates the wind resistance of asphalt shingles under standardized testing conditions.

GoNano reports testing under the Class F category.

UL 790 — Fire Performance

UL 790 evaluates roofing assemblies for external fire exposure.

Class A is the highest classification within this standard.

GoNano reports UL 790 Class A testing for its system.

Why Standards Matter

A vague claim like:

“stronger against storms”

is difficult for a homeowner to evaluate.

A recognized test gives you:

• Defined procedure
• Defined classification
• A way to ask for documentation

Testing Does Not Make a Failed Roof a Candidate

This remains critical.

Performance testing of a treatment does not mean a rotten or structurally failed roof should be rejuvenated.

The roof still has to qualify first.

Ask for the Standard, Not Just the Superlative.

NanoTech Exteriors uses GoNano technology whose manufacturer publishes specific third-party testing information homeowners can review before making a decision.