Which material is commonly used for the decking in pitched roofs?

• A. Wire mesh
• B. Aluminum sheeting
• C. Oriented Strand Board (OSB)
• D. Heavy timbers

Answer: (C)

Decking needs a flat, strong base that can support fasteners for underlayment and roofing materials while withstanding wind and weather. Oriented Strand Board (OSB) fits this role well because it’s an engineered wood panel that is uniform in thickness and surface, strong, and cost-effective. Its design provides good nail grip and resists warping, making it reliable for the continuous decking surface on pitched roofs. It’s easier and quicker to install than solid lumber, and it offers the necessary stiffness to support the roofing system above. Other materials mentioned don’t serve as the deck: wire mesh isn’t a continuous surface for fastening shingles, heavy timbers are typically used for structural framing rather than the decking surface, and aluminum sheeting is usually a roofing material rather than the deck itself.