Which of the following is NOT a focus of the Residential Building Code?

The correct choice identifies an area that falls outside the scope of the Residential Building Code. The Residential Building Code is primarily concerned with construction standards, safety, energy efficiency, and performance requirements specific to residential buildings. This includes ensuring compliance with structural integrity, implementing energy efficiency measures, and addressing safety concerns in residential electrical systems.

Commercial signage, however, pertains to regulations and codes that govern commercial properties, which are not part of residential building considerations. The Residential Building Code does not address the requirements for signage related to commercial facilities, making it the option that does not align with the primary focus areas of the code. This distinction is important for building officials and construction professionals who must understand the limitations and specific applications of residential regulations.