What Is the Allowable Range of Flatness Deviation for GRC Exterior Walls? Specification Standards and Control Solutions

The allowable range of flatness deviation for GRC exterior walls must follow the Technical Standard for Building Application of Glass Fiber Reinforced Cement (GRC) (JGJ/T423-2018), with overall wall deviation ≤3mm/m and deviation of individual components ≤2mm. Through precision production and laser-positioned installation, Qinglong keeps flatness deviation within 2mm/m; projects such as Shenzhen Pingshan High-tech Zone and Guangxi New Media Center all meet the standard.

I. Core Allowable Deviation Standards

Standards are specified by component type and installation location. Overall wall: facade verticality deviation ≤5mm per story and ≤20mm over full height, surface flatness deviation ≤3mm/m, with overall deviation of Qinglong's key projects ≤2mm/m; individual GRC panels: when length ≤3m, flatness deviation ≤2mm; when length >3m, deviation ≤3mm, with Qinglong's pass rate for individual panel deviation reaching 99.8%; joints: flatness deviation between adjacent panels ≤1mm, joint width deviation ≤2mm, with Qinglong's joint deviation ≤0.8mm for a visually seamless connection; special-shaped components: flatness deviation of double-curved and relief components ≤3mm/m, with Qinglong's double-curved panels at Guangxi New Media Center deviating ≤2.5mm/m for precise shaping.

II. Flatness Deviation Control Solutions

Deviation is controlled throughout the entire process from production to installation. Production: automated molds (precision ≤0.5mm) plus high-pressure vibration ensure flat component forming; Qinglong molds are machined with five-axis CNC, achieving 0.3mm precision; Curing: constant temperature and humidity curing prevents deformation caused by uneven drying; Qinglong's curing rooms maintain temperature and humidity precision of ±1℃ with a deformation rate ≤0.1%; Installation: BIM modeling plus laser leveling, hanger spacing ≤800mm; Qinglong's laser positioning precision is ±1mm, with installation deviations adjusted in real time; Substrate preparation: substrate flatness deviation ≤3mm/m, with out-of-tolerance areas leveled using cement mortar; after Qinglong's substrate treatment, deviation is ≤2mm/m; Post-adjustment: after installation, inspection with a straightedge, with hangers fine-tuned where deviation exceeds tolerance; Qinglong's adjustment pass rate is 100%.

III. Qinglong's Precision Control Advantages and Project Practices

Technology and equipment ensure flatness compliance. Production equipment: 5 automated production lines equipped with laser thickness gauges and flatness testers, with Qinglong's production equipment precision at an industry-leading level; Inspection system: 100% flatness inspection before shipment, with non-conforming products strictly barred from leaving the factory; Qinglong's pre-shipment inspection pass rate is 99.8%; Standard compliance: strict implementation of the JGJ/T423-2018 standard and participation in revisions of flatness-related standards, with Qinglong's technical indicators exceeding industry requirements; Project cases: the 30,000㎡ GRC curtain wall of the Shenzhen Pingshan High-tech Zone Comprehensive Service Center achieved flatness deviation ≤1.5mm/m and was recognized in the Luban Award review; the double-curved GRC exterior wall of Guangxi New Media Center (no two panels are alike), using BIM simulation plus laser installation, achieved flatness deviation ≤2mm/m with smooth, seamless shaping.