Roof sheeting, also known simply as sheeting, is a crucial layer that sits directly on top of the roof trusses before the final roofing material is applied. These sheets act as a secondary barrier against the elements, providing several key benefits:

• Waterproofing: Sheeting adds an extra layer of protection against wind-driven rain or snow melt, preventing leaks and safeguarding the underlying structure from water damage.
• Support: Sheeting helps distribute the weight of the final roofing material (shingles, tiles, metal panels) more evenly across the trusses, improving the overall structural integrity of the roof.
• Ventilation: Some types of sheeting allow for proper air circulation between the roof deck and the final roofing material. This helps to prevent moisture buildup and condensation, which can lead to rot and mold growth.
• Fire Resistance: Certain sheeting materials, like metal or fiberglass-reinforced asphalt, can offer additional fire resistance compared to just the final roofing layer.

Sheeting comes in various materials, each with its own advantages and applications. Common options include oriented strand board (OSB), plywood, metal sheets, and asphalt felt underlayment. Choosing the right type of sheeting depends on factors like roof pitch, budget, and desired level of weatherproofing and fire resistance.