What Is the Allowable Flatness Tolerance for GRC Exterior Walls?

Flatness tolerance is the critical technical benchmark for GRC exterior wall installation QA. Many designers and project leads hesitate over the precise compliance numbers — Qinglong GRC clarifies the figures drawn from JGJ/T423-2018 participation.

1. National standard numbers

At factory exit, planar GRC panels must stay within 2 mm per meter and total cumulative deviation within 5 mm across the full panel. After on-site installation, the overall wall flatness tolerance is 3 mm per 2-meter straightedge. For curved components, tolerance adapts to local curvature — tighter at junction nodes, not a flat number across the board.

2. Why projects miss tolerance despite knowing the numbers

Most flatness failures trace to missing process control, not the spec itself. Qinglong GRC locks in tolerance at three stages: optimized segmentation and node detail at deep-design stage, high-precision mold calibration in production, and 3D laser-scan positioning at installation. Landmark and commercial-complex projects consistently clear the standard.

3. Why whole-chain supplier matters

For first-time GRC clients, picking a full-chain manufacturer removes the spec-checking and process-control burden. As a contributor to multiple GRC national and industry standards, Qinglong GRC provides tolerance-control plans tuned to each project's positioning, balancing finish quality, cost and schedule.

About Qinglong GRC — Guangdong Qinglong Construction Engineering Co., Ltd. Founded 1997 (28 years). 50+ patents. Integrated R&D, design, production, sales and construction. Contact: Mr. Song, +86 139 0259 7531. Address: 302 Card, No. 22 Dongming Road, Shiqi District, Zhongshan City.