Drainage Design of Container Houses

The drainage design of container houses should take into account the roof form, building scale, and climatic conditions. Organized drainage should be the main approach, and measures such as reasonably dividing drainage areas, setting drainage slopes and gutters, and selecting appropriate downspouts should be adopted to ensure the rapid discharge of rainwater and prevent leakage.

1. Drainage Method Selection

The drainage methods for container houses are divided into organized drainage and unorganized drainage.

• Organized drainage: It is suitable for multi-story, large-span container houses or those with high drainage efficiency requirements. Rainwater is guided to downspouts through roof water-diverting devices (such as gutters and eaves gutters) and then discharged to the ground or the rainwater system. For example, multi-span factories or high-rise container buildings often use internal gutter drainage to prevent rainwater overflow.
• Unorganized drainage: It is only suitable for low-rise, small-span container houses or those with an eaves height of less than 10 meters. Rainwater directly falls freely from the roof to the ground, but attention should be paid to controlling the catchment area to avoid water accumulation.

2. Key Points of Drainage System Design

1. Drainage Area Division and Slope Control

   • The roof should be divided into several drainage areas. The width of a single-slope drainage roof should not exceed 12 meters to ensure the rapid collection of rainwater.
   • The drainage slope should be determined according to the roof material, generally not less than 2% to avoid water accumulation. For example, metal roofs can achieve drainage through structural slopes or material slopes.

2. Gutter and Eaves Gutter Design

   • Gutters: They are suitable for multi-span or large-span container houses. They are set in the middle of two spans and slope towards the end wall. The net width should not be less than 200 millimeters, and the distance from the highest point of the longitudinal slope to the upper opening should not be less than 120 millimeters. When the length of the gutter exceeds 20 meters, additional drainage outlets should be added to reduce the slope-finding length.
   • Eaves gutters: They are suitable for single-span or small container houses. They are set along the roof edge and drain water through downspouts (risers). The spacing between downspouts is generally 15 - 20 meters, and the pipe diameter should not be less than 75 millimeters. Each downspout can discharge rainwater from an area of about 200 - 250 square meters of the roof.

3. Downspout Selection and Arrangement

   • The inner diameter of the downspout should not be less than 75 millimeters. The material can be PVC or metal pipes, which should be corrosion-resistant and tightly connected.
   • The spacing between downspouts should be determined according to the rainfall intensity and the roof catchment area, generally 18 - 24 meters. For example, in areas with heavy rainstorms, the spacing should be shortened to avoid poor drainage.

3. Special Scenario Handling

• High-rise buildings or buildings with high facade requirements: An internal drainage system should be adopted, with rainwater heads and hanging pipes set inside the building to avoid the impact of exposed pipes on the appearance.
• Cold regions: Pipe anti-freezing measures should be considered. Electric tracing or increasing the pipe slope can be used to prevent water accumulation and freezing.
• Large-span roofs: For example, arched roofs, rainwater troughs and reinforced drainage pipes should be set to withstand the impact of large water flows and prevent structural damage.

4. Waterproof and Anti-seepage Measures

• Roof waterproof layer: Waterproof membranes or coatings should be used to ensure that the roof has no cracks and prevent rainwater penetration.
• Joint treatment: The joints between gutters, eaves gutters, and the roof should be strengthened in terms of waterproofing, with additional layers or sealants set.
• Regular maintenance: Clean debris from the gutters and check for blockages in the downspouts to ensure the smooth operation of the drainage system.