Do additions to existing construction need to be tested? If so, which tests?
First, additions 200 square feet or less are exempt from the testing requirements. While the tests were intended for new construction, some of the tests can also be performed on – and are required for – larger additions to existing construction. For example, a bedroom addition would have to meet the room pressure differential requirement. The total air distribution system – existing as well as what is added to serve the new construction – can be tested for leakage with a blower door subtraction test. Airflow to the supplies in the new construction will need to be checked to make sure they are +/- 20% of design. Static pressure of the system will need to be checked to make sure it meets the code requirements.
