Comprehensive Property Inspections

Serving Central Texas

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2009 Code Compliance testing prior to city final inspections

Also see our gallery to view photo presentation on duct testing

Duct tightness shall be verified in one of three manners. They all revolve around pressurizing the air duct system to verify how much air leaks, primarily to the outside of the home from the ducts. This makes sense; we don’t want to spend money conditioning the vented attic.

Below is a description from the code and photos attached showing some of the highlights of the test.

The first choice discussed is a test during the rough-in period. It can be done with or without the air handler installed.

  • Rough-in test: Total leakage shall be less than or equal to 6 cfm per 100 ft2 of conditioned floor area when tested at a pressure differential of 0.1 inches w.g. (25 Pa) across the roughed in system, including the manufacturer’s air handler enclosure. All register boots shall be taped or otherwise sealed during the test. If the air handler is not installed at the time of the test, total leakage shall be less than or equal to 4 cfm per 100 ft2 of conditioned floor area.

The most common method is performed on the finished home.

  • Postconstruction test: Leakage to outdoors shall be less than or equal to 8 cfm per 100 ft2 of conditioned floor area or a total leakage less than or equal to 12 cfm per 100 ft2 of conditioned floor area when tested at a pressure differential of 0.1 inches w.g. (25 Pa) across the entire system, including the manufacturer’s air handler enclosure. All register boots shall be taped or otherwise sealed during the test.

Exceptions: Duct tightness test is not required if the air handler and all ducts are located within conditioned space i.e. ducts within a spray foamed sealed attic.