Final answer:
Fasteners for attaching plywood below grade should be made from Type 304 or Type 316 stainless steel due to their corrosion resistance properties, with Type 316 offering greater resistance inclusive of marine environments.
Step-by-step explanation:
The fasteners used below grade to attach plywood to the exterior side of a basement, crawlspace, or knee wall, shall be of Type 304 or Type 316 stainless steel. Fasteners for attaching plywood below grade should be made from Type 304 or Type 316 stainless steel due to their corrosion resistance properties, with Type 316 offering greater resistance inclusive of marine environments.
These types are chosen for their corrosion resistance properties, which is critical in environments where they may be exposed to moisture or chemicals found in soil. Type 304 stainless steel is a general-purpose stainless steel with good resistance to a wide range of chemicals, while Type 316 has even greater corrosion resistance, including to chlorides, making it ideal for marine environments.