Exterior wall layers, known as the building envelope, comprise several crucial components: cladding, insulation, air/vapor barrier, and sheathing. These layers work together to protect a building from weather elements, insulate interiors, control moisture levels, and enhance energy efficiency. Regulations and certifications, such as IBC and ASHRAE, ensure compliance with building standards. Design considerations involve aesthetics, durability, moisture management, and fire safety. Stakeholders include architects, builders, contractors, manufacturers, and homeowners, each playing a vital role in the functionality and performance of the exterior wall layers.