What is the minimum slope required for a sprayed polyurethane roof?

What is the minimum slope required for a sprayed polyurethane roof?

• A. One fourth unit vertical in 12 units horizontal
• B. One half unit vertical in 12 units horizontal
• C. One third unit vertical in 12 units horizontal
• D. One fourth unit vertical in 24 units horizontal

Answer: (A)

Drainage is the main issue here: sprayed polyurethane foam roofs must shed water to prevent ponding that can degrade the foam and protective coatings. The slope is the vertical rise per horizontal distance. For SPF systems, the standard minimum is 1/4 inch of rise for every 12 inches of horizontal run, about a 2% grade. This ensures water flows toward edges or drains rather than pooling on the surface. The other options would create a steeper slope than needed or, in the shallow case, not provide enough drainage to prevent ponding. So the minimum slope is 1/4 inch per 12 inches.

Drainage is the main issue here: sprayed polyurethane foam roofs must shed water to prevent ponding that can degrade the foam and protective coatings. The slope is the vertical rise per horizontal distance. For SPF systems, the standard minimum is 1/4 inch of rise for every 12 inches of horizontal run, about a 2% grade. This ensures water flows toward edges or drains rather than pooling on the surface. The other options would create a steeper slope than needed or, in the shallow case, not provide enough drainage to prevent ponding. So the minimum slope is 1/4 inch per 12 inches.