Key Design Points for Roof Drainage of Single-Curvature GRC Panels

When single-curved GRC panels are used for roofing, the drainage design directly affects functionality and durability. Based on experience from multiple large-scale roofing projects, Qinglong Group has summarized three key design points—slope control, joint treatment, and drainage organization—to ensure smooth roof drainage without leakage.

Slope design is the foundation of drainage. The minimum slope for single-curved roof panels should be no less than 3%, increasing to 5% at critical areas. In the Hainan International Convention and Exhibition Center project, Qinglong Group used BIM models for drainage simulation and optimized panel surface curvature, keeping rainwater concentration time within 5 minutes. Guide grooves are set on the panel surface, 30-50mm wide and 10-15mm deep, to direct rainwater discharge in an orderly manner. For large-span roofs, a bidirectional slope design is adopted to avoid localized ponding.

Joint treatment is a critical step. Panel joint width is determined by thermal deformation calculations, typically 15-20mm. Qinglong Group adopts a "triple waterproofing" design: a base sealant layer (polysulfide type), a middle drainage cavity, and a surface weather-resistant sealant (silicone type). A project in Shenzhen once experienced leakage due to improper joint design; after optimization and improvement, joints were redesigned using the pressure-equalized cavity principle, effectively eliminating the leakage.

The drainage system requires a complete design. Rainwater outlet spacing should not exceed 15m, with outlet size calculated based on the catchment area. Qinglong Group installs overflow systems in critical roofing projects to ensure smooth drainage during rainstorms. With scientific drainage design, single-curved GRC roofs can remain leak-free under a once-in-a-century rainstorm, with a service life of over 50 years.