Roofing nails should be long enough to penetrate through concrete roof tile and at least _____ into the roof deck.

The correct answer emphasizes the necessary penetration depth for roofing nails used with concrete roof tiles. Roofing nails must penetrate not only through the tile itself but also into the underlying roof deck to ensure a secure hold and withstand various environmental factors like wind uplift and heavy rain.

The requirement for a penetration depth of at least 3/4 inch into the roof deck is typically specified because this provides an adequate grip for the nails. It allows the nail to anchor firmly within the decking material, which can be plywood or oriented strand board (OSB), thereby preventing any potential loosening or displacement over time. A depth of 3/4 inch strikes a balance between achieving the necessary hold while also being manageable in terms of installation and minimizing damage to the roof deck that could occur with longer nails.

Longer nails, such as those that penetrate 1 inch or 1-1/4 inches, may not be practical as they can increase the risk of splitting the decking material or even penetrating too deeply, which can cause issues with membranes or insulation underneath. Thus, using a nail that penetrates at least 3/4 inch into the roof deck is the best practice for maintaining the integrity and longevity of the roof system.