How to Handle Joint Leakage in GRC Exterior Walls?

Leakage at GRC facade joints is a common quality defect that can be both prevented and remedied. Its treatment must follow the principles of "inspection and diagnosis, scientific treatment, and multiple lines of defense." From simple surface caulking to complex systematic repairs, remedies must be tailored to the specific cause of the leakage. Through years of maintenance services, Qinglong Group has developed standardized treatment processes for different types of leakage, efficiently and durably resolving joint leakage problems and restoring the integrity of the curtain wall system.

Step 1: Precise Inspection and Cause Diagnosis

Before treatment, the root cause of the leakage must be identified. Common causes include: 1) Sealant failure: aging and cracking, loss of adhesion to the substrate, or insufficient filling during installation. 2) Backing material problems: the use of open-cell foam rods forming a "water bridge"; or backing set too shallow, causing the "three-sided adhesion" of the sealant joint to tear apart. 3) Design defects in joint construction: insufficient joint width, with thermal deformation tearing the sealant joint; lack of a drainage system, leading to long-term water accumulation inside the joint. 4) Panel or structural deformation: excessive deformation of the substrate or the GRC panels themselves, exceeding the movement capability of the sealant. On-site observation, water spray testing, and even endoscopic exploration are needed to pinpoint the problem.

Step 2: Scientific Treatment Techniques and Material Selection

Corresponding treatment measures are adopted for different causes: 1) For localized sealant failure: thoroughly remove the original failed sealant and backing material, then clean and dry the substrate. Re-apply a highly elastic silicone sealant with excellent weather resistance, ensuring a proper depth-to-width ratio of the sealant joint (typically 1:2) and good adhesion to the substrates on both sides. 2) For construction defects: if the joint width is severely insufficient, the GRC panels must first be appropriately cut to widen the joint. Install a metal flashing above the joint to channel water flow. Ensure that closed-cell polyethylene foam rods are used as backing. 3) For leakage caused by deformation: check whether the connection system is loose and reinforce it if necessary. Afterwards, a sealant with higher movement capability (e.g., ±50% class) should be selected.

Step 3: Systematic Repair and Prevention

For extensive, multi-point joint leakage, the original sealing system may have aged as a whole, and a systematic replacement is recommended. Qinglong's standardized process includes: mock-up construction, material compatibility testing, zone-by-zone streamlined operations, and water spray acceptance testing. After treatment, a regular inspection regime should be established, especially after extreme weather. Prevention is better than cure: at the new construction stage, high-quality weather-resistant sealant should be selected, installation should be carried out according to standards, and joint construction should be rationally designed—this is the fundamental way to avoid future leakage problems.