Network Voice (Zhihu / Architectural Design Drawing Review Group):
“Every time we want to use a new material for the exterior wall, we dread fire safety and drawing review the most. If the code and local atlases don’t specify it and there is no precedent, the drawing review company can completely stall the project with a single sentence: ‘Please provide proof of Grade A non-combustibility and system construction basis.’ Flexible Stone claims to be A2, but it is a polymer composite. Will the fire department recognize it?”
Network Voice (Xiaohongshu / Contractor’s Rant):
“The biggest fear in high-rise retrofits is things falling off. In the past, a piece of dry-hung stone fell and smashed a car, and we were ruined paying compensation. Now we use Flexible Stone. Although it’s light, it’s attached to an exterior wall dozens of meters high. When a typhoon comes, if the whole sheet is blown off, is that the ‘Sword of Damocles’? The client chases us every day for pull-off test data.”
Network Voice (Overseas Architecture Forum / Shadows after the Grenfell Tower Fire):
“Since Grenfell, our building control officers scrutinize every single cladding material. They don’t care how cheap it is. If you can’t show me an EN 13501 classification or ASTM E84 report proving it won’t propagate fire, and prove how it’s mechanically fixed, it’s a hard NO for anything above 18 meters.”
Network Voice (A Local Fire Acceptance Site Dialogue):
“The drawings show Flexible Stone as A2 grade, but does this batch on site have the corresponding test report? Also, the insulation layer is B1 grade—is the protective layer thick enough? Has the fire barrier been installed according to code? We can’t accept the system just by looking at a single material report.”
Analysis and Summary: The Confidence to Pass Drawing Review Lies Not in “Good Material,” but in a “Closed-Loop Evidence Chain” and “System Interruption”
For high-rise exterior wall finishes, they are both the “facade” and the “safety bottom line” hanging over the public’s heads. From the perspective of fire safety and drawing review, the doubts surrounding Flexible Stone can be broken down into two swords: one is the chemical “Sword of Fire” (will it burn, will it drip and ignite the floors below), and the other is the physical “Sword of Wind” (will it be blown off and injure people). The core of passing drawing review is to put a solid lock on these two swords.
First Lock: Securing Chemical Safety—Responding to the “Sword of Fire” with “A2-s1, d0.”
Many drawing review experts have a natural vigilance against “composite materials” because traditional aluminum composite panels (with polyethylene cores) melt and drip in a fire, accelerating vertical fire spread (the culprit behind the Grenfell Tower tragedy). Flexible Stone must play its highest card: the SGS A2-s1, d0 report issued according to GB 8624-2012.
- Grade A2: Represents non-combustible materials with extremely low calorific value (PCS), suitable for high-rise buildings and densely occupied spaces.
- Grade s1: Very low smoke production (SMOGRA 21.2 m²/s²); it does not produce smoke that obscures vision during a fire.
- Grade d0: No flaming droplets within 600 seconds. This clause directly cuts off the fatal path of “droplets igniting floors below” and is an absolute bonus point for passing drawing review.
- Compliance Narrative: Drawing review doesn’t just look at the material’s A2 rating; it also looks at system fire protection. Flexible Stone is A2 as a facing layer, but the exterior wall insulation system (such as rock wool strips, protective layers, and fire barriers) must be designed as a whole according to GB 50016/GB 55037 to form a complete fire protection structure.
Second Lock: Securing Physical Safety—Responding to the “Sword of Wind” with “Lightweight + Full Coverage.”
Fall prevention is another crucial point for high-rise buildings. Traditional dry-hung stone relies on heavy keels and hanging pieces; once the anchorage fails, it becomes a lethal heavy object. Why does Flexible Stone have more confidence in physical safety?
- Extreme Lightweight: SGS measured surface density is only 3.96 kg/m² (2mm thick). Even in a limit-state detachment from a high-rise, its kinetic energy is far less than that of stone or thick ceramic tiles weighing tens of kilograms.
- System Bonding: When passing drawing review, the system construction plan of “special flexible adhesive + full coverage rate ≥ 80% + pull-off test ≥ 0.4MPa” must be presented. The construction notes on drawings must strictly prohibit “spot bonding or partial bonding”; they must emphasize “thin-set full coverage” and “substrate strength ≥ 0.3MPa.” As long as the system bonding meets standards, it is a layer of “skin” tightly attached to the wall, and its wind pressure and seismic resistance are far higher than cavity-based dry-hanging systems.
Third Lock: Drawing Compliance and Acceptance Traceability—Building a “Closed-Loop Evidence Chain.”
Drawing review and fire acceptance do not review a single “material”; they review the documentation.
- Design End: The design brief must cite JG/T 311 and JC/T 2219 standards, and attach the SGS A2-s1, d0 test report and the Class A radioactivity report in the general notes.
- Construction End: Incoming re-inspection (verifying batch numbers), concealed works acceptance (recording substrate treatment, primer, full coverage rate), and on-site pull-off test records.
- Acceptance End: Archiving of fire safety documents. When facing the question “Is what’s on site consistent with the drawings?”, provide complete batch number traceability records and photo/video documentation.
Conclusion: The “Sword of Damocles” over high-rise exterior walls fears three things: “burning through at a touch, blowing off in a gust, and shifting blame when something happens.” The underlying logic for Flexible Stone to pass drawing review and fire acceptance is: using the SGS A2-s1, d0 report to interrupt fire spread, using the 3.96 kg/m² lightweight and full-coverage system to prevent high-altitude falls, and using a complete testing and construction record chain to interrupt responsibility shifting. Only by upgrading “material compliance” to “system-compliant delivery” can this sword truly be lifted from the minds of the reviewers.