What is required to permanently seal the annular spaces around penetrations for vents through outside walls?

To permanently seal the annular spaces around penetrations for vents through outside walls, it is essential to use approved materials. This requirement is based on safety standards and building codes that ensure proper sealing to prevent gas leaks, moisture intrusion, and deterioration of materials over time. Approved materials are specifically designed to meet regulatory safety standards, providing assurance that they will function effectively and safely in a variety of environmental conditions.

Using approved materials helps to create a robust and secure seal, minimizing risks associated with gas venting and safeguarding the integrity of the building. It also ensures compliance with local and national codes, which is critical for the safety of occupants and the environment.

Other options like insulation materials, plywood sheets, and steel plates may not be suitable or authorized for this specific purpose. Insulation materials might lack the necessary properties to create a permanent seal, while plywood sheets or steel plates do not meet the requirements of approved sealing methods as dictated by regulations. Thus, using approved materials is the best practice to ensure both safety and compliance.