Measures to Prevent Rainwater Leakage in Steel Structure Factory Building Enclosure Systems

Casey Thompson

As the Chief Technology Officer, Casey drives innovation in钢结构 engineering by integrating cutting-edge technologies into our projects. His leadership has positioned Huajian as a tech-savvy leader in the industry.

Roof leakage is a common issue in steel structure factory buildings, frequently occurring at profiled sheet overlaps, skylight strips, gutters, and roof ridges. Causes include inadequate drainage design, defective joint detailing, and material deformation due to temperature fluctuations. The following measures are designed to prevent rainwater leakage in the enclosure systems of such buildings.

I. Roof Slope and Drainage Design

Roof slope directly affects drainage efficiency. In regions with heavy rainfall or snowfall, the slope of wide-span roofs should not be less than 10%. Gutters must meet local drainage requirements based on rainfall volume; the number and diameter of downpipes must be matched to the roof slope length; gutter steel plates should not be too thin; and welded joints must be tight and seamless.

II. Joint Overlapping and Sealing

Longitudinal overlaps should follow the direction of water flow. Overlap lengths should be at least 300 mm for slopes less than 1:10 and at least 200 mm for slopes greater than 1:10, with waterproof sealing strips applied between the upper and lower sheets. Ridge cap plates should be widened, with sealant applied at overlap points; closure plugs must match the sheet profile, with sealing material placed both above and below them. Skylight edge trim must be securely sealed to the roofing sheets, and sealant widths on both longitudinal sides should be appropriately increased to prevent capillary water seepage.

III. Selection of Waterproofing Materials

Butyl sealant is suitable for concealed joints and requires mechanical compression to ensure long-term waterproofing performance, whereas polyurethane sealant is suitable for exposed joints and interfaces between dissimilar materials. Silicone sealant is not suitable for use in metal enclosure systems. Sealant must be applied correctly at overlap points to prevent leakage risks caused by aging or detachment.

IV. Key Construction Control Points

Foam closure plugs should be installed simultaneously with the roof sheets, and the outer roof sheets should be bent downwards by 30 degrees. Flashing details at locations such as eaves, gables, and parapets must incorporate drip edges; the vertical leg of the flashing panel must have an effective height of at least 250 mm and be securely fastened. Openings must be treated in accordance with design specifications, ensuring sufficient clearance around the perimeter for drainage. Taking local climatic conditions into account, select panels with appropriate corrugation heights (high or medium profile), and align the panel overlaps with the prevailing wind direction.