ANSI/DASMA 105 - Test Method for Thermal Transmittance and Air Infiltration of Garage Doors

When a garage door manufacturer publishes a U-factor or R-value, that number is only meaningful if it was measured by a real test. ANSI/DASMA 105 is that test. It defines exactly how to set up a door specimen and measure its thermal performance.

What this standard says

ANSI/DASMA 105-2017 establishes the procedure for testing garage door thermal transmittance (U-factor) and air infiltration. The standard specifies:

"This test method covers procedures for measuring the steady-state thermal transmittance (U-factor) and air infiltration of sectional garage doors and other door systems, including the test specimen setup, conditions, and calculation methods."

The standard requires testing the full door assembly, including weather seals and any gaps at the edges and bottom. This is important because a loose-fitting door with high-R panels can still underperform if the seals leak air.

U-factor measures heat flow through the door per square foot per degree of temperature difference. A lower U-factor means better insulation. R-value is the inverse of U-factor (R = 1/U). Manufacturers must use ANSI/DASMA 105 test results to report U-factors through DASMA's thermal performance verification program.

Air infiltration is tested separately under the same standard. It measures how much air leaks through the door assembly at a given pressure difference.

When it applies

ANSI/DASMA 105 results matter in two main situations:

Comparing energy performance between doors. Manufacturer brochures sometimes list R-value per panel without testing the whole assembly. A whole-door U-factor measured under ANSI/DASMA 105 accounts for the frame, seals, and edge gaps. For example, a door listed at R-16 per panel might show a whole-door U-factor of 0.19 (R-5.3) once leakage paths are included. Always compare whole-door U-factors from ANSI/DASMA 105 tests, not just panel R-values.

Energy code submittals in Denver. The International Energy Conservation Code (IECC) references ANSI/DASMA 105 for garage door thermal performance. Denver's 2025 building code follows the 2024 IECC. If your project requires energy code compliance for an attached garage, the door's U-factor must be documented from an ANSI/DASMA 105 test.

DASMA thermal verification program. DASMA maintains a database of doors tested under ANSI/DASMA 105. A door listed in that program has been independently verified. This is more reliable than a self-reported manufacturer spec.

What this means for you

Ask for the whole-door U-factor, not just panel R-value. The two numbers tell different stories. U-factor from an ANSI/DASMA 105 test accounts for the complete assembly.

Attached garages in Denver benefit from tested insulation. An attached garage shares a wall with the house. A well-insulated, well-sealed door reduces heat loss through that assembly.

Verify the source of any U-factor claim. A valid ANSI/DASMA 105 result will name the test lab and the door model tested. If a manufacturer cannot point to test documentation, the number may be a panel-only estimate.

G Brothers can provide ANSI/DASMA 105 test documentation for the insulated door models we carry.

Full text and source

ANSI/DASMA 105-2017 is available at https://www.dasma.com/wp-content/uploads/2022/03/ANSI-DASMA-105-2017-DASMA.pdf.

ANSI/DASMA 105 applies to sectional garage doors. Rolling steel doors and other door types use different test methods. R-value and U-factor requirements vary by climate zone under IECC; confirm the applicable zone for your project with Denver CPD.