Reasons for Dampness in Prefabricated Houses

There are several main reasons for dampness in prefabricated houses:

Rising moisture from the foundation soil is one of the common causes of dampness in prefabricated houses. The moisture in the foundation soil rises to the walls through capillary action. If traditional buildings do not have an effective damp-proof layer, the foundation walls will absorb this moisture and gradually spread it upwards. This capillary action is similar to the process by which plant roots absorb water, where the moisture in the soil forms a continuous column of water in tiny pores and continuously moves upwards, ultimately leading to damp walls.

Condensation of air moisture is also an important factor. When the moisture in the air comes into contact with the inner surface of walls with a large temperature difference, condensation occurs. For example, in winter, the indoor temperature is relatively high while the wall temperature is low. The moisture in the air condenses into water droplets when it touches the cold wall surface, causing the wall to become damp. This situation is particularly evident in poorly ventilated houses because the moisture cannot be discharged in a timely manner and tends to accumulate on the inner surface of the walls.

Rainwater infiltration cannot be ignored either. Rainwater may seep into the interior of the house through gaps in the exterior walls. In traditional construction, if the waterproofing treatment of details such as construction joints and door and window openings is not precise enough, these areas are prone to become weak links for water seepage. Once rainwater infiltrates, it will not only cause damp walls but may also lead to more serious structural problems.

Problems with storage or construction environment can also affect the dryness of prefabricated houses. For example, if prefabricated floor slabs are stored in open areas or exposed to rain, they will absorb a large amount of moisture. In addition, if the prefabricated floor slabs are located near damp buildings and environments, such as sewer pipes and bathrooms, they are also susceptible to moisture erosion. The moisture generated by cement, mortar, and other materials at the construction site may also penetrate into the prefabricated floor slabs in a humid environment, causing dampness problems.

The impact of extreme weather is also a cause of dampness in prefabricated houses. In extreme weather conditions such as heavy rain, the prefabricated panels are continuously eroded by rainwater for a long time, and the accumulated water around them gradually seeps in and out, leading to dampness. This situation is particularly severe in areas with poor drainage systems or low-lying terrain.