AF103.4.8, Ducts, is deleted in its entirety and the following provisions shall apply:

Ductwork passing through or beneath a slab shall be of seamless material unless the air-handling system is designed to maintain continuous positive pressure within such ducting. Joints in such ductwork shall be sealed to prevent air leakage.

Ductwork located in crawl spaces shall have seams and joints sealed by closure systems in accordance with Uniform Mechanical Code.

AF103.11, Building depressurization, is deleted in its entirety and the following provisions shall apply:

Joints in air ducts and plenums in unconditioned spaces shall meet the requirements of Uniform Mechanical Code. Thermal envelope air infiltration requirements shall comply with the energy conservation provisions in Chapter 11. Fireblocking shall meet the requirements contained in Section R302.11.