The lift coefficient for concrete and clay tile shall be:

• A. 0.10
• B. 0.20
• C. 0.30
• D. 0.40

Answer: (B)

When estimating wind uplift on a roof, a lift coefficient translates the dynamic wind pressure into an uplift load on the roof surface. For concrete and clay tile roofs, the standard lift coefficient used in Florida practice is 0.20. This value reflects the balance between the weight and interlocking/fastening of the tiles, which provides substantial resistance to uplift, and the wind forces acting on the surface. In calculation terms, the uplift load per area is the dynamic pressure times 0.20, so using a higher coefficient would overstate uplift and a lower one would understate it. Therefore, 0.20 is the appropriate value for these tile roofs.