Underground Dampness in Container Houses

Underground dampness in container houses can be addressed with targeted measures, covering moisture-proof design, added equipment, floor treatment, and routine maintenance.

Causes of Dampness

• Environmental factors: In humid or rainy regions, air moisture is high. In hot, humid areas such as Guangdong, average annual humidity often reaches 80%, creating conditions for condensation. If the ground is uneven, drains poorly, or has not been hardened, rainwater and groundwater can seep under the container base; long rainy seasons and high groundwater levels in Guangdong make the problem worse.
• Structural design issues: Older or second-hand containers often have poor bottom sealing and gaps. Some container floor materials have weak moisture resistance—ordinary steel, for example, rusts easily. Missing floor insulation, insufficient thickness, or use of moisture-absorbing materials fails to block heat exchange, so floor temperature can drop below the dew point.
• Use and maintenance issues: Transporting cargo with high moisture content, or cargo that produces condensation, can leave the container floor damp. Long periods without cleaning the floor, with standing water and dirt, also worsen dampness.

Solutions

• Choose a suitable container: Prefer containers designed for moisture resistance, such as those with rust-resistant materials and sealed construction, or containers from manufacturers known for strong moisture performance.
• Add moisture-control equipment: Install a small exhaust fan on the container roof, paired with intake vents at the bottom to create airflow. For long closed periods, use a dehumidifier as well. When storing items day to day, place desiccant packs or activated carbon bags inside vacuum storage bags.
• Floor treatment: Lay moisture-proof mats inside, or pour concrete and apply waterproof membrane. Slightly elevate the container house so air can circulate between the base and the ground.
• Walls, roof, and sealing: Coat walls with moisture-proof paint; seal door and window gaps; check and seal roof gaps, and add insulation batting on the exterior.
• Routine maintenance: Wipe interior walls and floors regularly and dry condensation promptly. Store goods on shelves or wooden racks raised off the floor. Pack clothing in vacuum bags; coat metal tools with rust-preventive oil or wrap them in moisture-barrier film. For outdoor use, add a sun/rain canopy and dig simple drainage ditches.