Chapter 11
Applicable Boundaries and Unsuitable Scenarios: Which Walls Cannot Be Applied with Flexible Stone
Compiled by Guangdong Fortune Stone New Material Co., Ltd.
Key Points
Flexible stone is not universal. Choosing the right material is technique; using it in the right scenario is wisdom.
Flexible stone’s applicable boundaries are divided into a three-layer structure: core zone recommended for use, transition zone used with caution, and forbidden zone prohibited for use.
Four non-negotiable boundaries: cannot be applied when substrate strength is insufficient and untreated; cannot be applied when long-term immersion in water without waterproofing; cannot be applied when fire rating does not meet standards without reports; interior-grade products must not be passed off as exterior wall products.
Four scenarios requiring cautious use: high temperature and heavy oil fume, frequent mechanical wear, long-term acid-base corrosion, and unstable structural deformation.
Applicability determination follows a five-step process: substrate determination, environmental determination, compliance determination, economic determination, and decision determination.
Three principles of boundary management: do not cross boundaries, do not take chances, do not conceal.
11.1 The Three-Layer Structure of Flexible Stone Applicable Boundaries
Flexible stone’s applicable boundaries can be divided into three levels: core zone, transition zone, and forbidden zone.
Core zone (recommended for use): substrate firm, dry, flat, no water seepage, non-high-temperature and heavy-oil-fume environment, non-long-term water immersion environment. In these scenarios, flexible stone’s performance advantages can be fully utilized.
Transition zone (used with caution): substrate conditions general, requiring treatment before use; special climate environment, requiring specific formulas; special building type, requiring customized schemes. In these scenarios, flexible stone can be used, but additional technical measures need to be taken.
Forbidden zone (prohibited for use): substrate strength severely insufficient and untreated, long-term water immersion without waterproofing system, special fire rating requirements but reports unavailable, low-priced interior-grade products passed off as exterior wall products. In these scenarios, flexible stone cannot be used; otherwise, problems will inevitably occur.
Table 11-1 Three-Layer Structure of Flexible Stone Applicable Boundaries
| Level | Scenario Characteristics | Usage Recommendation | Risk Level |
|---|---|---|---|
| Core zone | Good substrate, no water seepage, non-special environment | Recommended for use | Low |
| Transition zone | General substrate, special climate, special building | Used with caution, requiring technical measures | Medium |
| Forbidden zone | Poor substrate, long-term water immersion, fire rating non-compliant | Prohibited for use | High |
11.2 Four Non-Negotiable Boundaries
11.2.1 Boundary One: Original Substrate Strength Insufficient and Untreated—Cannot Be Applied
Technical determination: substrate strength less than 0.3 MPa, and no primer treatment or re-plastering; substrate dusting, chalking, hollowing area greater than 20%; substrate moisture content greater than 10%.
Risk analysis: The substrate is the “foundation” of the flexible stone system. If substrate strength is insufficient, the bonding agent cannot bond firmly, and flexible stone will inevitably hollow and detach. This risk has a high probability of occurrence and serious consequences, and must be avoided.
Treatment scheme: For insufficient substrate strength, remove and re-plaster, apply primer after curing; for substrate dusting, clean and apply primer, re-plaster if necessary; for substrate hollowing, remove hollowing parts and re-plaster; for substrate moisture content exceeding standards, wait for drying or take drying measures.
The independently developed non-migratory flexible stone emulsion technology, through reactive emulsifiers, enables emulsion particles to stably bond with polymer surfaces, reducing interface defects caused by emulsifier migration and improving flexible stone’s interface stability under complex substrate conditions. But it must be clarified: this technology improves the emulsion’s own adaptability to substrates; it cannot replace substrate treatment. If the substrate does not meet standards, it still cannot be applied.
Script: “This substrate strength is insufficient. If flexible stone is applied directly, it will definitely fall off in half a year. Let’s treat the substrate first, then apply flexible stone. Spending a little more time now is better than reworking later.”
11.2.2 Boundary Two: Long-Term Water Immersion Without Waterproofing System—Cannot Be Applied
Technical determination: long-term water immersion environment (such as swimming pool inner walls, water tanks, long-term water accumulation areas); no waterproofing system or waterproofing system failed; substrate moisture content long-term greater than 10%.
Risk analysis: Although flexible stone has good water resistance, long-term water immersion will cause bonding agent hydrolysis, substrate softening, and flexible stone hollowing and detachment. This risk has a medium probability of occurrence and serious consequences, and should be resolutely avoided.
Treatment scheme: For long-term water immersion environments, ceramic tiles or special waterproofing materials are recommended; if flexible stone must be used, a waterproofing system must be done first to ensure the substrate is dry; the waterproofing layer must be compatible with the bonding agent.
Script: “This part is immersed in water for a long time. No matter how water-resistant flexible stone is, it cannot withstand it. Ceramic tiles or stainless steel are recommended. If flexible stone must be used, waterproof first, but the cost will be much higher.”
11.2.3 Boundary Three: Special Fire Rating Requirements but Reports Unavailable—Cannot Be Applied
Technical determination: building height greater than 100 m, requiring Class A fireproof materials; densely populated places, requiring Class A fireproof materials; flexible stone combustion performance reports do not meet design requirements.
Risk analysis: Fire protection is a field with strong externalities, and compliance is a non-negotiable red line. Without fire protection reports, drawing review will not pass, fire acceptance will not pass, and the project will be stalled. This risk has a high probability of occurrence and extremely serious consequences, and must be avoided.
Treatment scheme: Confirm the fire rating required by the design; provide test reports for the corresponding grade; if unavailable, recommend replacing the material.
Script: “This project requires Class A fire protection, and our product is B1. It’s not that we don’t want to do it; the standard does not allow it. Class A materials are recommended, or the design scheme should be adjusted.”
11.2.4 Boundary Four: Low-Priced Interior-Grade Products Passed Off as Exterior Wall Products—Directly Rejected
Technical determination: product test report marked as “for interior wall use”; product performance indicators do not meet exterior wall requirements (weather resistance, freeze-thaw resistance, salt spray resistance); price significantly lower than exterior wall products.
Risk analysis: Interior-grade and exterior-grade products have different formulas and performance standards. Interior-grade products passed off as exterior wall products have insufficient weather resistance and will fade, chalk, and crack within one or two years. This risk has a high probability of occurrence and serious consequences, and must be rejected.
Treatment scheme: Check test reports to confirm product use; check performance indicators to confirm compliance with exterior wall requirements; refuse to use interior-grade products passed off as exterior wall products.
Script: “This test report says interior wall use; it cannot be used on exterior walls. Exterior walls must withstand sun and rain; interior-grade products cannot withstand it. We cannot risk the entire project to save this little money.”
Table 11-2 Four Non-Negotiable Boundaries
| Boundary | Technical Determination | Risk Level | Treatment Scheme | Script Points |
|---|---|---|---|---|
| Insufficient substrate strength | Less than 0.3 MPa, untreated | High | Treat substrate before construction | Spend time now rather than rework later |
| Long-term water immersion without waterproofing | No waterproofing system | High | Replace material or waterproof | Even water-resistant flexible stone cannot withstand long-term immersion |
| Fire rating non-compliant | No corresponding grade report | Extremely high | Replace material | Standards do not allow it; cannot be done |
| Interior-grade passed off as exterior wall | Report marked interior wall use | High | Directly reject | Cannot risk the project to save money |
11.3 Four Scenarios Requiring Cautious Use
11.3.1 Scenario One: High Temperature and Heavy Oil Fume Environment
Scenario characteristics: kitchen exhaust outlets, restaurant exterior walls, industrial plant exhaust areas.
Risk analysis: High temperature will accelerate flexible stone aging, and heavy oil fume will cause surface contamination.
Treatment scheme: Flexible stone not recommended; if it must be used, select high-temperature-resistant and oil-resistant formulas, and shorten maintenance cycles. The independently developed stain-resistant topcoat technology can increase surface whiteness recovery rate to over 80%, improving surface cleanliness in high-temperature and heavy-oil-fume environments. But it must be clarified: this technology solves the “stain resistance” problem, not the “high temperature resistance” problem. For scenarios with long-term temperatures exceeding 80°C, ceramic tiles or stainless steel are still recommended.
Table 11-3 High Temperature and Heavy Oil Fume Scenario Assessment
| Assessment Item | Assessment Content | Conclusion |
|---|---|---|
| Temperature range | Long-term greater than 80°C | Not recommended |
| Oil fume concentration | Heavy oil fume environment | Not recommended |
| Alternative scheme | Ceramic tiles, stainless steel | Recommended |
11.3.2 Scenario Two: Frequent Mechanical Wear Areas
Scenario characteristics: parking lot entrances and exits, logistics passages, industrial plant walls.
Risk analysis: Frequent mechanical wear will cause surface scratches and damage to flexible stone.
Treatment scheme: Flexible stone not recommended; if it must be used, select high wear-resistant formulas and provide finished product protection.
11.3.3 Scenario Three: Long-Term Acid-Base Corrosion Environment
Scenario characteristics: chemical plant buildings, pickling workshops, coastal areas with severe salt spray.
Risk analysis: Long-term acid-base corrosion will cause flexible stone performance degradation and surface discoloration.
Treatment scheme: Ordinary flexible stone not recommended; if it must be used, select chemical corrosion-resistant formulas. The independently developed high-flexibility flexible stone emulsion technology can adapt to -30°C low-temperature environments, withstand 100 freeze-thaw cycles without cracking or peeling, and has weather resistance of 3500h, capable of adapting to the harsh environments of coastal areas with high temperature, high humidity, and salt spray corrosion. But it must be clarified: this technology improves weather resistance; for strong acid-base corrosion environments (such as chemical plant buildings), special chemical corrosion-resistant formulas are still required.
11.3.4 Scenario Four: Buildings with Unstable Structural Deformation
Scenario characteristics: new buildings (not yet past settlement period), buildings under structural renovation.
Risk analysis: Structural deformation will cause flexible stone cracking and detachment.
Treatment scheme: Construct after structural stabilization; if construction must proceed, reserve deformation joints and select high-flexibility formulas. The independently developed high-flexibility flexible stone emulsion technology keeps flexible stone flexible at -30°C, withstanding 100 freeze-thaw cycles, capable of adapting to a certain degree of substrate deformation. But it must be clarified: this technology solves the “temperature deformation” problem, not the “structural settlement” problem. For new buildings not yet past the settlement period, construction after structural stabilization is still recommended.
Table 11-4 Four Scenarios Requiring Cautious Use
| Scenario | Risk | Treatment Scheme | Alternative Scheme | Independent R&D Technology Support |
|---|---|---|---|---|
| High temperature and heavy oil fume | Accelerated aging, contamination | High-temperature-resistant formula | Ceramic tiles, stainless steel | Stain-resistant topcoat technology |
| Frequent mechanical wear | Scratches, damage | High wear-resistant formula | Metal panels, stone | None |
| Long-term acid-base corrosion | Performance degradation, discoloration | Corrosion-resistant formula | Special anti-corrosion materials | High-flexibility emulsion technology |
| Unstable structural deformation | Cracking, detachment | Construct after stabilization | Delay construction | High-flexibility emulsion technology |
11.4 The Determination Process of Applicable Boundaries
11.4.1 Five Steps of the Determination Process
Step one: substrate determination. Is substrate strength greater than or equal to 0.3 MPa? Is substrate moisture content less than or equal to 10%? Is substrate flatness less than or equal to 4 mm/2 m? Is there substrate hollowing?
Step two: environmental determination. Is there long-term water immersion? Is there high temperature and heavy oil fume? Is there frequent mechanical wear? Is there long-term acid-base corrosion?
Step three: compliance determination. Does the fire rating meet design requirements? Do environmental requirements meet standards? Are standard bases complete?
Step four: economic determination. Is the life cycle cost reasonable? Is the rework risk controllable?
Step five: decision determination. Core zone is recommended for use; transition zone is used with caution; forbidden zone is prohibited for use.
Table 11-5 Applicable Boundary Determination Process
| Step | Determination Content | Determination Standard | Non-Conformance Handling |
|---|---|---|---|
| 1 Substrate determination | Strength, moisture content, flatness, hollowing | — | Treat substrate |
| 2 Environmental determination | Water immersion, high temperature, wear, corrosion | — | Replace material |
| 3 Compliance determination | Fire protection, environmental protection, standards | — | Replace material |
| 4 Economic determination | Life cycle cost, rework risk | — | Evaluate subsequent decisions |
| 5 Decision determination | Core zone/transition zone/forbidden zone | — | Execute according to determination |
11.4.2 Determination Checklist
Table 11-6 Flexible Stone Applicability Determination Checklist
| No. | Determination Item | Determination Standard | Conclusion |
|---|---|---|---|
| 1 | Substrate strength | Greater than or equal to 0.3 MPa | □ Yes □ No |
| 2 | Substrate moisture content | Less than or equal to 10% | □ Yes □ No |
| 3 | Substrate flatness | Less than or equal to 4 mm/2 m | □ Yes □ No |
| 4 | Substrate hollowing | No hollowing | □ Yes □ No |
| 5 | Long-term water immersion | No long-term water immersion | □ Yes □ No |
| 6 | High temperature and heavy oil fume | No high temperature and heavy oil fume | □ Yes □ No |
| 7 | Frequent mechanical wear | No frequent wear | □ Yes □ No |
| 8 | Long-term acid-base corrosion | No long-term corrosion | □ Yes □ No |
| 9 | Fire rating | Meets design requirements | □ Yes □ No |
| 10 | Environmental requirements | Meets environmental standards | □ Yes □ No |
| 11 | Product use | Exterior wall-specific | □ Yes □ No |
| 12 | Life cycle cost | Reasonable | □ Yes □ No |
If all 12 items are “Yes,” it can be determined as suitable for use; if any “No” exists, implement treatment measures item by item and re-determine; if key safety items (substrate strength, fire rating, product use) are “No,” directly determine as unusable.
11.5 The “Three Principles” of Boundary Management
11.5.1 Do Not Cross Boundaries
Core meaning: Know where the boundaries are and resolutely do not cross them.
Practical points: Do not construct when substrate does not meet standards; do not bid when fire rating does not meet standards; do not pass off interior-grade products as exterior wall products.
Common misconception: Taking orders by force.
11.5.2 Do Not Take Chances
Core meaning: Do not take chances, do not gamble on “it should be fine.”
Practical points: Treat substrate problems first; do not “apply because it looks okay”; replace materials when fire rating does not meet standards; do not “report because it might pass.”
Common misconception: Applying because it looks okay.
11.5.3 Do Not Conceal
Core meaning: Truthfully inform boundaries and do not conceal risks.
Practical points: When the client asks “can it be used,” answer truthfully; when the design institute asks “is it okay,” inform truthfully; when the construction party asks “can it be applied,” explain truthfully.
Common misconception: Concealing risks to close the deal.
Table 11-7 Three Principles of Boundary Management
| Principle | Core Meaning | Practical Points | Common Misconception |
|---|---|---|---|
| Do not cross boundaries | Know boundaries, resolutely do not cross | Do not construct when substrate does not meet standards | Taking orders by force |
| Do not take chances | Do not gamble on “it should be fine” | Treat problems first | Applying because it looks okay |
| Do not conceal | Truthfully inform boundaries | Answer truthfully whether it can be used | Concealing risks to close the deal |
11.6 Decision Reference for Facade Retrofit Offices
Key Decision Points of This Chapter
- Whether flexible stone can be used in a specific facade retrofit project cannot be decided by experience alone; it should be checked item by item according to the five-step process of “substrate determination, environmental determination, compliance determination, economic determination, and decision determination.”
- Four boundaries are non-negotiable: cannot be applied when substrate strength is insufficient and untreated; cannot be applied when long-term water immersion without waterproofing; cannot be applied when fire rating does not meet standards without reports; interior-grade products passed off as exterior wall products cannot be applied.
- Three principles of boundary management: do not cross boundaries, do not take chances, do not conceal. Saying “cannot be used” requires more responsibility than saying “can be used.”
Compliance Check Items
- Verify substrate strength test reports, confirming substrate strength not less than 0.3 MPa; verify substrate moisture content test records, confirming not greater than 10%.
- Verify the use marked on product test reports; exterior wall projects must use exterior wall-specific products, and interior-grade products passed off as exterior wall products are strictly prohibited.
- Verify fire rating test reports, confirming compliance with building fire protection code requirements for building height and use place.
- Verify the consistency between incoming products and test reports, focusing on thickness, surface density, combustion performance, and other indicators.
Cost Reference Range
- Substrate treatment costs are necessary costs for flexible stone construction in facade retrofit projects, including removal, re-plastering, primer, curing, etc.; specific costs are based on actual engineering quantities; omitting substrate treatment will multiply later rework costs.
- Special requirements such as waterproofing systems, high-temperature-resistant formulas, and corrosion-resistant formulas will increase comprehensive costs and need to be fully evaluated at the scheme stage.
- Rework costs caused by improper selection of low-carbon technology materials, including idle time costs, material loss costs, and management fees, usually far exceed material price differences.
Risk Warnings
- Forced construction under conditions of insufficient substrate strength and excessive moisture content is the primary risk source of flexible stone hollowing and detachment, and may cause safety accidents.
- Mismatched fire rating reports may lead to drawing review failure, fire acceptance failure, and project stagnation, which are unacceptable risks.
- Low-priced interior-grade products passed off as exterior wall products have insufficient weather resistance and will fade, chalk, and crack within one to two years, with extremely high secondary repair costs.
Replicability Judgment
Strictly screening projects according to applicable boundaries and determination processes can significantly reduce flexible stone quality risks in facade retrofit and improve engineering replicability.
- For projects in the “transition zone,” technical measures such as substrate treatment and formula adjustment should be completed first, and sample wall verification should be conducted before promotion.
- For projects in the “forbidden zone,” materials should be resolutely replaced, and the idea that “flexible stone can replace all facade retrofit exterior wall materials” should not be promoted.
Reflections on Stone, Insights on Fortune
Saying “can be used” requires technique; saying “cannot be used” requires courage.
References
[1] JG/T 311—2011, Flexible Facing Brick[S]. Beijing: Standards Press of China, 2011.
[2] JC/T 2219—2014, Modified Inorganic Powder Composite Building Facing Sheet[S]. Beijing: China Building Materials Industry Press, 2014.
[3] JGJ 126—2015, Specification for Construction and Acceptance of Exterior Wall Facing Tile Engineering[S]. Beijing: China Architecture & Building Press, 2015.
[4] GB 50210—2018, Standard for Construction Quality Acceptance of Building Decoration[S]. Beijing: China Architecture & Building Press, 2018.