Duct Leakage Testing Services
Duct Leakage Testing
Total duct leakage is a measurement of the amount of air loss expressed in cubic feet per minute (CFM) at 25 Pascals, which is about the typical air pressure when an air handler unit is operating.
All intentional openings in the duct work, such as supplies and returns, are sealed, to pressurize the duct work and measure the amount of airflow lost at 25 Pascals.
The CFM25 is divided by the conditioned area served by the duct system. This represent CFM25 / 100 sq. ft., or normalized duct leakage (Qn).
Total duct leakage is the accepted method to measure duct system air loss for residential energy code.
Duct Leakage Code Requirements
Maryland
West Virginia
Maryland
Less than
4 CFM25 / 100 sq ft
100% duct testing required, including ducts 100% in conditioned space.
Adoption and enforcement varies by jurisdiction.
Delaware
West Virginia
Maryland
Less than
4 CFM25 / 100 sq ft
Duct work in 100% conditioned space is exempt.
Virginia
West Virginia
West Virginia
Less than
4 CFM25 / 100 sq ft
Duct work in 100% conditioned space is exempt. Adoption and enforcement varies by jurisdiction.
Required in
King George County, VA
West Virginia
West Virginia
West Virginia
Less than
4 CFM25 / 100 sq ft
100% duct testing required, including ducts 100% in conditioned space. Adoption and enforcement varies by jurisdiction.
Required in
Charles Town, WV