What unit is used to specify the thickness of a vapor retarder?

What unit is used to specify the thickness of a vapor retarder?

• A. Mil
• B. Inch
• C. Centimeter
• D. Meter

Answer: (A)

Measuring the thickness of a vapor retarder uses a unit that captures very thin sheets. In practice, the thickness is expressed in mils, where one mil is one thousandth of an inch. Common vapor barriers are about 6 mil or 10 mil thick, which is roughly 0.15 to 0.25 mm. Using inches would lack the fine resolution needed for these thin materials, and centimeters or meters would imply a thickness far thicker than a typical vapor retarder. So mil is the standard unit.

Measuring the thickness of a vapor retarder uses a unit that captures very thin sheets. In practice, the thickness is expressed in mils, where one mil is one thousandth of an inch. Common vapor barriers are about 6 mil or 10 mil thick, which is roughly 0.15 to 0.25 mm. Using inches would lack the fine resolution needed for these thin materials, and centimeters or meters would imply a thickness far thicker than a typical vapor retarder. So mil is the standard unit.