What Is the Allowable Range of Flatness Deviation for GRC Exterior Walls? Precision Standards and Qinglong Group's Process Control

The flatness of individual GRC facade panels and the overall flatness of the facade are key indicators affecting a building's visual effect and optical quality. According to the national industry standard "Technical Standard for Building Application of Glass Fiber Reinforced Cement (GRC)" (JGJ/T423) and the internal control requirements based on Qinglong Group's 28 years of engineering practice, the allowable flatness deviations for GRC facade panels are typically: when checked with a 2-meter straightedge, the panel surface flatness deviation should not exceed 3mm, and the surface height difference between adjacent panels should not exceed 2mm. For high-end public buildings or visually prominent areas, Qinglong Group's internal control standards are stricter, often keeping flatness within 2mm/2m.

Achieving high flatness is a systematic project spanning the entire process of design, production, and installation. In the design stage, panel segmentation and rib layout must be reasonably designed to prevent deformation caused by insufficient stiffness. In the production stage, mold precision is fundamental—Qinglong Group uses CNC-machined steel molds or high-precision tooling board molds to ensure the molds themselves have extremely high flatness. The spraying or casting process must be uniform, and the curing process must ensure that panels are evenly stressed to prevent warping. In the installation stage, the connection system must offer three-dimensional adjustment capability so that each panel can be precisely leveled. During the acceptance inspection of a super high-rise project in Shenzhen, we used a laser level to conduct a comprehensive inspection of the GRC curtain wall, and the overall flatness fully met and even exceeded the design standards.

Flatness control concerns not only aesthetics but also functionality. Excessive unevenness creates visually chaotic light spots and, on rainy days, may cause localized water accumulation that accelerates staining and erosion. Qinglong Group treats flatness as a core mandatory inspection item in both factory inspection and on-site acceptance, and panels that fail to meet the requirements are firmly withheld from leaving the factory or being installed. Through refined control across the entire process, we ensure that every delivered GRC facade project achieves excellent visual flatness.