7.4 Unvented Enclosed Exposures

Examples of unvented enclosed exposures are enclosed areas such as wall cavities, enclosures surrounded by breakaway walls under elevated buildings, and floor framing cavities created when finishes are installed on the underside of floor joists.

Because of the limited airflow and incoming salt spray, corrosion rates for connectors in these exposures are expected to be lower than the rates in partially sheltered exterior exposures, open exposed exterior exposures, or vented enclosed exposures. However, since many connectors and fasteners installed in unvented enclosed exposures are concealed by finishes and would require removing building materials to gain access to the fasteners, inspection to evaluate their condition is generally impractical. Therefore, installing corrosion-resistant (or more corrosion-resistant) fasteners and metal connectors in these areas should be considered a responsible construction practice.