Which building element found in Type V construction is likely to produce dense, dark, oily toxic smoke when it burns?

• A. Vinyl siding
• B. Industrial glue
• C. Exterior wall cavities
• D. Prefabricated wood truss system

Answer: (A)

In Type V construction, which relies on combustible, light-frame methods, finishes and components often involve plastics and other petroleum-based materials. Vinyl siding is a common exterior finish made from PVC, and when it burns it releases heavy, dense, dark smoke that can have an oily appearance, along with toxic gases like hydrogen chloride. This combination of material, location, and smoke characteristics makes vinyl siding the most likely to produce that specific, dense oily smoke described in the question. Other choices—such as interior adhesives, wall cavities, or structural wood trusses—do burn and emit toxins, but they aren’t as consistently associated with that distinctive dense, dark, oily smoke signature tied to burning vinyl siding.