6.6.7 Airtightness

To limit the infiltration of contaminants from outside the building into the building envelope, building construction should be made as airtight as possible. Tight construction practices (weatherization techniques, tightly sealing windows, doors, wall construction, continuous vapor barriers, sealing interface between wall and window/door frames) will also help to maintain the desired pressure relationships between HVAC zones. To ensure that the construction of the building has been performed correctly, building commissioning is recommended throughout the construction process and prior to taking ownership to observe construction practices and to identify potential airflow trouble spots (cracks, seams, joints, and pores in the building envelope and along the lines separating unsecured from secured space) before they are covered with finish materials.