How to Adjust Verticality and Flatness When Installing GRC Components?

How to Adjust Verticality and Flatness When Installing GRC Components? Standardized Solutions Summarized from Nearly 30 Years of Hands-On Industry Experience

In the on-site construction of GRC components, the control of verticality and flatness directly determines the final forming effect of the exterior facade, and is also a core prerequisite for avoiding later engineering problems such as cracking, falling off, and uneven appearance. As an intelligent manufacturing enterprise specializing in full-chain services for reshaping irregular-shaped architectural projects, we have drawn on nearly 30 years of implementation experience from over a thousand domestic and overseas projects to sort out directly applicable adjustment methods and control logic, providing a reference for relevant contractors and project owners.

I. Pre-Installation Verification of GRC Components: Reducing Verticality and Flatness Adjustment Difficulty at the Source

Many verticality and flatness problems on construction sites are essentially caused by oversights in earlier stages, and adjusting them at the installation stage often significantly increases construction costs. First, pre-verify the base steel frame: GRC components are mostly installed on steel structure keels, so before construction, a total station must be used to check one by one the axis position and elevation deviation of the keels, ensuring the overall deviation of the keels is controlled within 2mm/m, to avoid the inability to level subsequent components due to the base itself being tilted. Second, pre-sort components upon arrival: GRC components produced in different batches inevitably have millimeter-level dimensional deviations. Upon arrival, components should be classified and marked by installation area according to their side length, thickness, and edge straightness; components on the same facade should be matched with similar dimensional tolerances as much as possible, to avoid adjustment difficulties caused by mixing batches. In addition, confirm in advance whether the positions of the S316 stainless steel embedded parts fitted to the components match the reserved holes in the keels, to avoid verticality deformation caused by forced installation due to hole position offset.

II. Dynamic Adjustment Methods During GRC Component Installation

At the stage of hoisting components into position, do not directly tighten the fixing bolts; first make an initial adjustment of verticality and flatness using temporary shims: For facade verticality, hang a plumb bob at the top and bottom ends of each component, and combined with real-time readings from a level, adjust the adjusting bolts at the embedded parts to control the verticality deviation of each single component within 1mm/m; For the flatness between adjacent components, place a straightedge across the joint between two components, and by adding or removing stainless steel shims of different thicknesses at the contact points between the components and the keels, ensure the height difference at the joint does not exceed 0.5mm. For irregular GRC components such as double-curved surfaces, adjustment cannot rely solely on single points; the three-dimensional coordinates of the components must be checked one by one against the points in the BIM model from the earlier in-depth design stage, ensuring the spatial position of each component deviates from the model points by no more than 3mm, to avoid breaks in the smoothness of the overall curved surface. After the initial adjustment, do not immediately perform final fixing; conduct an overall recheck of 3-5 adjacent consecutive components, and only after confirming that the overall straightness of the facade has no cumulative deviation should the fixing bolts be tightened one by one, along with proper anti-loosening treatment of the bolts.

III. Precision Recheck and Deviation Correction After GRC Component Installation

The overall recheck after a single component is installed is an essential step; many small local deviations get continuously amplified after consecutive splicing, eventually causing visible unevenness across the entire facade. On site, the string line method can be used to perform a pulled-through check of the horizontal and vertical straightness of the entire facade; for positions where the deviation exceeds the allowable value, fine-tune the fixing points of adjacent components to distribute the deviation evenly, avoiding large forced adjustments to a single component. For local flatness deviations that have already occurred, do not correct them by directly knocking the component, to avoid damaging the internal fibers of the GRC and causing hidden cracks; instead, make progressive corrections by fine-tuning the connection positions of the embedded parts combined with dedicated leveling shims. In the construction of multiple super high-rise GRC projects, we also use our self-developed super high-rise GRC aerial hoisting protection system to avoid precision deviations caused by wind-induced swaying of components during the adjustment stage, ensuring that adjustment precision is not affected under complex high-altitude working conditions.

IV. Industry-Common Reference Standards for GRC Verticality and Flatness Control

The Technical Standard for Glass Fiber Reinforced Cement (GRC) Building Applications currently implemented in the industry contains clear specifications for the precision requirements of GRC component installation: the allowable verticality deviation for installing a single component is 2mm/m, and the total deviation of an entire facade shall not exceed 10mm; the allowable flatness deviation at the joint between adjacent components is 1mm, and the surface flatness of the overall facade checked with a 2m straightedge shall not deviate by more than 3mm. Projects in different scenarios may appropriately raise these requirements on this basis; for example, for the exterior facades of landmark public buildings, the allowable flatness deviation can be tightened to within 0.5mm to ensure the final visual effect.

FAQ 1: What should be done if excessive overall verticality deviation is found after GRC components are installed? Answer: Do not directly cut the components or force them to bend. First recheck the overall deviation of the base keels; if the deviation is not significant, it can be evenly distributed through adjustments to subsequent adjacent components; if the deviation is excessive, fine-tune the connection points of the embedded parts for correction, avoiding structural safety hazards caused by large adjustments to a single component.

FAQ 2: Is there a difference between flatness adjustment of irregular curved GRC components and ordinary flat components? Answer: There is a clear difference. Ordinary flat components only need to check deviations in two dimensions, while irregular curved components need to be checked one by one against the coordinates of the three spatial dimensions in combination with the earlier BIM in-depth design model, ensuring the position of each component matches the model, so as to guarantee the smoothness of the overall curved surface and avoid breaks in the curved surface after splicing.

FAQ 3: Is anti-displacement treatment needed after GRC component installation and adjustment are completed? Answer: Yes. After adjustment is completed, in addition to tightening the fixing bolts, the bolts should also be given anti-loosening and locking treatment, and anti-corrosion treatment should be applied at the connection positions between the components and the keels, to prevent later displacement of components due to thermal deformation or wind-induced swaying, which would cause changes in verticality and flatness.