According to the "Quality Acceptance Code for Building Decoration and Renovation Projects" (GB 50210-2001), the permissible deviation and inspection method for the installation of concealed frame and semi-concealed frame glass curtain walls are as follows:

Verticality of curtain wall: When the curtain wall height is ≤30m, the permissible deviation is 10mm; when the curtain wall height is 30m＜curtain wall height≤60m, the permissible deviation is 15mm; when the curtain wall height is 60m＜curtain wall height≤90m, the permissible deviation is 20mm; when the curtain wall height is＞90m, the permissible deviation is 25mm.

Horizontality of curtain wall: When the curtain wall width is ≤35m, the permissible deviation is 5mm; when the curtain wall width is＞35m, the permissible deviation is 7mm.

Surface flatness of curtain wall: the permissible deviation is 2mm.

In addition, different standards and specific project requirements may vary. In actual construction and acceptance, it is also necessary to conduct inspections based on specific project design requirements and relevant standards. At the same time, the process and quality should be strictly controlled during the construction process to ensure that the flatness of the glass curtain wall meets the requirements.

If you need to know more detailed or specific standards, you can refer to the relevant building specifications or consult professional curtain wall design and construction personnel.