Why Are Container Houses Damp?
The main reasons for dampness in container houses include condensation due to temperature differences, infiltration of external moisture, moisture from the cargo itself, high air humidity, improper insulation layer design, and other factors.
Condensation due to temperature differences: When there is a temperature difference between the inside and outside of a container house, water vapor in the air condenses into water droplets on cooler surfaces. For example, during the day, the temperature inside the container may rise above 60 degrees Celsius, while at night it may drop sharply to below freezing, or turning on the air conditioner may cause the floor temperature to fall below the dew point of the indoor air, both of which can trigger condensation. In winter, with a large temperature difference between indoors and outdoors, the warm indoor water vapor can turn into small water droplets when it comes into contact with the cold metal roof.
Infiltration of external moisture: Container designs typically include ventilation holes, through which external moisture may seep into the container. If the container is placed directly on unhardened mud or grass, ground moisture can also seep upward through capillary action, further exacerbating moisture accumulation inside the container, especially noticeable in humid environments. For example, in Guangdong, where the rainy season is long and the groundwater level is high, placing the container directly on the ground can worsen the problem of ground moisture infiltration.
Moisture from the cargo itself: The cargo itself may contain moisture, such as wood with a moisture content ranging from 8% to 25%, which can be released into the air, increasing the humidity inside the container. When the cargo has high moisture content, the water vapor it releases can significantly increase the moisture content of the indoor air, providing more 'raw materials' for condensation. For example, one ton of wood can secretly release 400 to 1250 liters of water vapor.
High air humidity: In regions with high temperatures and humidity, such as Guangdong, where the average annual humidity is often around 80%, the air itself contains a large amount of water vapor, providing ample 'raw materials' for condensation. When encountering temperature differences or surface cooling, the water vapor can easily condense into water droplets.
Improper insulation layer design: If the floor insulation layer is missing, insufficient in thickness, or has poor thermal insulation properties (such as using moisture-absorbing materials), it cannot effectively block heat exchange, making the floor temperature more likely to fall below the dew point, leading to dampness.
Other factors: Leaks in the roof or walls of the container house allow rainwater to seep into the room through gaps; poor design or blockage of the ground drainage system can cause rainwater to accumulate around the house and then seep into the interior; leaks in water pipes, drainage pipes, and other facilities inside the container house can also lead to water infiltration.
