The building envelope including the foundations has to comply the weather-resistant norms subjected in the codes.

CALGreen Code Section 5.407.1: Weather protection.

Provide a weather-resistant exterior wall and foundation envelope as required by California Building Code, Section 1402.2 (Weather Protection), and manufacturer’s installation instructions or local ordinance, whichever is more stringent.

Intent:

The intent of this code requirement is to provide a weather-resistant exterior wall and foundation envelope as currently required by the California Building Code, but go beyond those existing code provisions, increasing the integrity and longevity of the structure.

Compliance Method:

Determine local conditions that may affect the amount of moisture that might penetrate the envelope due to weather, wind-driven rain or exposure to salt spray, etc., for that particular climate zone. Design and detail exterior wall systems to reflect local findings, specifying appropriate materials and vapor retarder as applicable. Show on the construction documents.

Note: Pay special attention to openings and changes of material in detailing exterior wall systems. Exterior insulation and finish systems, if not installed to manufacturer’s instructions, have the potential for moisture penetration and condensation that may lead to mold, decreased longevity and potential structural failure.

Enforcement:

Plan intake: The plan reviewer should confirm in the construction documents that the exterior wall and foundation envelope meet California Building Code, Section 1402.2, Weather Protection, manufacturers installation instructions and any local ordinances.

On-site enforcement: The inspector should verify that the exterior wall and foundation envelope are installed in accordance with the approved construction documents.

(Excerpted from ‘Guide to the 2019 California Green Building Standards Code Nonresidential’ – Chapter 5)