502.4.3 Continuous Air Barrier

Except in unheated structures and as permitted by this section, a continuous air barrier shall be installed; sealing all seams, openings, and penetrations of the building and shall be sealed with caulking materials or closed with gasketing systems compatible with the construction materials and location. Joints and seams shall be sealed in the same manner or taped or covered with a moisture vapor-permeable wrapping material. Sealing materials spanning joints between construction materials shall allow for expansion and contraction of the construction materials. Such air barrier shall have all the following characteristics:

1. Continuous throughout the envelope with all joints and seams sealed and with sealed connections between all transitions in planes and changes in materials and at all penetrations.
2. Joined and sealed in a flexible manner to the air barrier component of adjacent assemblies, allowing for the relative movement of these assemblies and components.
3. Installed in accordance with the manufacturer's instructions and in such a manner as to achieve the performance requirements.
4. Penetrations of the continuous air barrier shall be made in a way such that the integrity of the continuous air barrier is maintained.

Compliance for continuous air barriers may be demonstrated using any one of the following three methods:

1. Materials. Using individual materials that have an air permeability not to exceed 0.02 L/s • m² under a pressure differential of 75 Pa [0.004 cfm/ft² under a pressure differential of 0.3 in. water (1.57 lb/ft²)] when tested in accordance with ASTM E 2178.
2. Assemblies. Assemblies of materials and components shall have an average air leakage not to exceed 0.2 L/s•m² under a pressure differential of 75 Pa [0.04 cfm/ft² under a pressure differential of 0.3 in. water (1.57 lb/ft²)] when tested in accordance with ASTM E 2357 or ASTM E 1677. In addition these assemblies must meet the requirement for joints per Section 502.4.3.
3. Building. Testing the completed building and demonstrating that the air leakage rate of the building envelope does not exceed 2.0 L/s•m² under a pressure differential of 75 Pa [0.4 cfm/ft² at a pressure differential of 0.3 in. water (1.57 psf)] in accordance with ASTM E 779 or an equivalent approved method.