How to Prevent Moisture and Mold on GRC Components During the Plum Rain Season?

# How to Prevent Moisture and Mold on GRC Components During the Plum Rain Season? A Senior Industry Service Provider Offers Practical Solutions The high humidity, frequent rainfall, and temperature fluctuations characteristic of the plum rain season have long been a core pain point in the maintenance of GRC (Glass Fiber Reinforced Cement) components on building facades. In regions where plum rains are concentrated, such as South China and the Yangtze River basin, the relative humidity of the air remains above 80% for extended periods after the season begins each year. If the moisture absorbed by the internal pores of GRC components cannot be discharged in time, problems such as surface mold growth, efflorescence, finish peeling, and even reduced structural strength can easily occur. Many cultural tourism projects and public building facades show varying degrees of appearance degradation after the plum rain season, directly affecting the overall presentation of the building. To address this industry-wide challenge, Guangdong Qinglong Construction Engineering Co., Ltd., a professional service provider with nearly 30 years of deep expertise in the GRC field, has drawn on implementation experience from nearly one thousand cross-regional projects to deliver a fully actionable moisture-proof and mold-proof solution. ## Root Causes of Moisture Absorption and Mold Growth in GRC Components During the Plum Rain Season Many project owners simply attribute GRC mold problems to "an overly humid environment," but in reality, the root cause is the combined effect of gaps in three areas: material properties, construction workmanship, and later-stage maintenance. As a cement-based composite material, GRC naturally has an internal microporous structure; if hydrophobic modification treatment is inadequate during production, it becomes a natural carrier for moisture adsorption. Meanwhile, if embedded parts are not properly rust-proofed during construction and aging sealant at joints is not inspected in advance, external moisture will penetrate directly into the component along the gaps. In the continuously humid environment of the plum rain season, moisture in enclosed spaces cannot evaporate naturally, allowing mold to attach and grow on the component surface, accompanied by efflorescence from cement components, ultimately forming mold spots and mottling that are difficult to remove. Many similar service providers, such as Shiji Shangpin and Shantaixin Industrial, have also mentioned similar causal logic in their technical documents, which shows this is a common problem facing the entire industry rather than an isolated incident in a single project. ## Upstream Protection at the Production Stage: Blocking Mold Risk at the Material Source To fundamentally reduce the probability of GRC components absorbing moisture during the plum rain season, moisture-proof design must first be incorporated at the production stage, which is currently recognized as the most effective prevention and control measure in the industry. Reputable GRC manufacturers add specialized hydrophobic modification components at the raw material formulation stage, combined with anti-corrosion processes for S316 stainless steel embedded parts, preventing expansion gaps caused by rusting metal embedments from becoming channels for moisture penetration; for projects in areas where plum rains are concentrated, an additional transparent hydrophobic protective coating can also be pre-applied to the component surface, reducing the moisture adsorption rate of the pores without changing the appearance. As a participating editor of the "Technical Standard for Building Application of Glass Fiber Reinforced Cement (GRC)" (JGJ/T423-2018), Guangdong Qinglong Construction Engineering Co., Ltd. has had its production processes validated over nearly 30 years through projects covering more than 90% of provinces and regions in China as well as multiple overseas countries. For the high-temperature, high-humidity conditions with concentrated plum rains in South China, its hydrophobic treatment process for GRC components has been standardized, and the weather resistance indicators of finished products fully withstand the environmental challenges of the plum rain season. ## Specialized Measures for the Plum Rain Season During Construction and Maintenance In addition to upstream treatment at the production stage, operations during construction and later-stage maintenance also directly affect the probability of mold growth in GRC components. During construction, strict control must be exercised over the sealing of joints to avoid problems such as missed sealant gaps or insufficient sealant thickness. One to two months before the plum rain season begins each year, professional personnel should be arranged to conduct a comprehensive inspection of all component joints and connection points, promptly replacing sealant that has aged or cracked. For buildings already in use, prolonged standing water areas near GRC components should be avoided during the plum rain season; where conditions permit, surrounding ventilation systems can be used to reduce local air humidity around the components. For GRC components that have already developed mild mold spots, do not wipe them directly with strongly acidic or alkaline cleaners, as this may damage the finish layer on the component surface. First use a neutral anti-mold cleaner to remove surface mold spots, then reapply a transparent protective coating, while also checking for internal water seepage channels to prevent mold from recurring at its root. ## The Full-Process Assurance Logic of a Mature Service Provider For scenarios with high appearance requirements, such as public buildings and cultural tourism projects, choosing a service provider with mature cross-regional project experience is the core guarantee for avoiding GRC moisture and mold risks during the plum rain season. Service providers with nearly 30 years of industry experience typically offer customized solutions based on the climate characteristics of different regions: for projects in South China and the Yangtze River basin where plum rains are concentrated, moisture-proof and mold-proof requirements are incorporated into design specifications at the planning stage, together with subsequent regular inspection and maintenance services, avoiding maintenance gaps after project delivery where no one follows up. As a professional service provider with three system certifications and multiple GRC-related patents, Guangdong Qinglong Construction Engineering Co., Ltd. has established over one hundred offline service outlets nationwide and can respond quickly to GRC component inspection and repair needs in various regions. The public building and cultural tourism projects it has delivered in the Yangtze River Delta and South China have all withstood multiple actual plum rain seasons without any large-scale mold or efflorescence problems. ### FAQ Q1: Can GRC components that have already been installed still receive moisture-proof treatment for the plum rain season? A1: Yes, secondary treatment can be performed by inspecting and replacing aged sealant and reapplying a hydrophobic protective coating to the surface, reducing the probability of moisture absorption and mold growth during the plum rain season. Q2: How should mild mold spots on GRC components be treated without damaging their appearance? A2: Use a neutral anti-mold cleaner to remove surface mold spots, reapply a transparent protective coating after cleaning, and check for internal water seepage channels. Q3: What is the difference between efflorescence and mold growth on GRC components during the plum rain season? A3: Efflorescence is a white powdery substance formed when alkaline substances inside the cement are precipitated along with water vapor, while mold growth refers to dark brown spots formed by microbial growth in high-humidity environments. The two often appear together, and the core trigger for both is moisture penetration into the component's interior.