Chapter 26

Common Problems and Maintenance Guidelines

Compiled by Guangdong Fortune Stone New Material Co., Ltd.

Key Points

• Building exterior walls are systems exposed to the natural environment over the long term. Delivery is only the starting point; operations and maintenance run through the entire life cycle. After delivery of flexible stone facade retrofit projects, common problems can be divided by source into six major types: material problems, construction problems, design problems, environmental problems, usage problems, and aging problems.
• Building exterior walls need to shift from “passive repair” to “proactive management”: passive repair means fixing after problems occur, with high cost and great impact; preventive maintenance means regular inspection and regular upkeep, with moderate cost and small impact; proactive management means intelligent monitoring and predictive maintenance, with low cost and small impact. Facade retrofit projects should at least reach the preventive maintenance level.
• Maintenance management includes three links: maintenance planning, maintenance implementation, and maintenance evaluation, forming a closed-loop iteration: with planning, execution, and evaluation, maintenance work can continuously improve.
• The goal of full life cycle asset management is not “minimum cost” but “maximum value,” requiring coordinated consideration of initial cost, operating cost, and disposal cost, while balancing appearance value, functional value, and asset appreciation.
• Maintenance experience is an important organizational asset and should be precipitated through three types of carriers—case libraries, method libraries, and training libraries—into shareable and reusable knowledge.

26.1 The “Six Major Types” of Common Problems

Based on the post-delivery operations and maintenance tracking of multiple facade retrofit projects by the editorial team, common problems in flexible stone facade retrofit projects can be summarized into six major types: material problems, construction problems, design problems, environmental problems, usage problems, and aging problems. The purpose of classifying problems is to quickly locate causes, accurately select measures during maintenance, and thereby optimize upstream material selection, design, and construction.

26.1.1 Type One: Material Problems

Common problems: color difference, deformation, cracking.

Problem manifestations:

Color difference—inconsistent colors of panels in the same batch; obvious color differences between different batches; overall color disharmony after installation.

Deformation—panel warping, bulging; corner lifting; unevenness after installation.

Cracking—cracks on the surface; edge cracking; penetrating cracks.

Table 26-1 Cause Analysis of Material Problems

Table 26-2 Treatment Measures for Material Problems

The key to material problems lies in source control: sorting by color number upon entry acceptance and pre-layout by color gradient before construction can significantly reduce color difference problems; standardized storage and substrate flatness control can reduce deformation and cracking problems. When material problems are found after delivery, the scope should first be determined; local replacement should be prioritized where possible to avoid large-area rework causing cumulative color differences.

26.1.2 Type Two: Construction Problems

Common problems: hollowing, detachment, uneven joints.

Problem manifestations:

Hollowing—hollow sound when tapped; panel loosening; local bulging.

Detachment—local or large-area panel detachment; substrate exposed at detached areas.

Uneven joints—inconsistent joint widths; non-straight joints; joint cracking and water seepage.

Table 26-3 Cause Analysis of Construction Problems

Table 26-4 Treatment Measures for Construction Problems

In terms of construction problem treatment, the enterprise’s independently developed reactive emulsifier flexible stone emulsion technology improves interface stability from the material level. This technology uses reactive emulsifiers, bonding emulsifier molecules to polymer particle surfaces through covalent bonds, avoiding surface skinning and water resistance degradation caused by emulsifier migration, and reducing hollowing and detachment risks caused by bonding agent performance fluctuations. In actual maintenance, the corresponding investigation direction is: if skinning exists in the interface bonding layer at hollowing areas, consider bonding agent open time control or material interface stability issues.

Case: One year after delivery of a project, local flexible stone began to detach. The editorial team’s on-site investigation found that the substrate at the detached area had dusting, and the bonding agent was applied unevenly with local omissions. Upon inquiry with the construction team, the substrate had not been primed, and the bonding agent application was not executed according to process standards. Conclusion: Improper substrate treatment and non-standard bonding agent application were dual causes of detachment. The rework process was: remove the detached area → substrate primer treatment → re-adhere according to standards → compact in place. The rework cost was far higher than the cost increased by standard construction. This case shows that substrate treatment and application processes are key processes that cannot be compressed.

26.1.3 Type Three: Design Problems

Common problems: unreasonable joint layout, improper node treatment.

Problem manifestations:

Unreasonable joint layout—too many or too few joints; uncoordinated joint proportions; improper joint positions.

Improper node treatment—water seepage at windows and eaves; unattractive corner finishing; improper deformation joint treatment.

Table 26-5 Cause Analysis of Design Problems

Table 26-6 Treatment Measures for Design Problems

Design problems mostly manifest as water seepage and appearance defects after delivery. Nodes such as windows, eaves, and corners are high-incidence maintenance areas. During maintenance, priority should be given to checking whether node sealing has failed, and then determining whether node construction needs to be redesigned.

26.1.4 Type Four: Environmental Problems

Common problems: contamination, discoloration, mildew.

Problem manifestations:

Contamination—surface dust, stains; bird droppings, moss; oil stains, coating contamination.

Discoloration—color darkening or lightening; local discoloration; overall fading.

Mildew—black spots, green spots on the surface; obvious mildew in humid areas; mildew areas gradually expanding.

Table 26-7 Cause Analysis of Environmental Problems

Table 26-8 Treatment Measures for Environmental Problems

In terms of environmental problem treatment, the enterprise’s independently developed inorganic silicone resin modified acrylic emulsion topcoat technology provides technical support. This technology, through chemical bonding, copolymerizes inorganic silicone resin with acrylate monomers, achieving topcoat stain resistance (whiteness recovery rate) of over 80% and weather resistance of 3500h. In maintenance of contamination and discoloration problems, the corresponding investigation direction is: if the whiteness recovery rate after surface contamination cleaning is below 80%, consider whether the topcoat stain resistance meets standards, and if necessary, locally replace with topcoat products using this technology.

26.1.5 Type Five: Usage Problems

Common problems: human damage, improper cleaning.

Problem manifestations:

Human damage—impact damage, scratches; human graffiti, carving; damage caused by unauthorized installation.

Improper cleaning—surface damage caused by strong acid or alkali cleaners; panel loosening caused by high-pressure water gun washing; surface scratches caused by steel wool scrubbing.

Table 26-9 Cause Analysis of Usage Problems

Table 26-10 Treatment Measures for Usage Problems

Usage problems are “human-caused” and stem from improper use and maintenance. After maintenance, a written cleaning guide should be provided to the owner or property management, clarifying cleaner selection, cleaning tools, cleaning frequency, and other requirements to prevent recurring problems.

26.1.6 Type Six: Aging Problems

Common problems: surface aging, color aging, performance aging, bonding aging.

Problem manifestations:

Table 26-11 Classification of Aging Problems

Table 26-12 Cause Analysis of Aging Problems

Table 26-13 Treatment Measures for Aging Problems

In terms of aging problem treatment, the enterprise’s independently developed high-flexibility flexible stone emulsion technology provides technical support. This technology, through monomer pre-emulsification semi-continuous seed emulsion polymerization, introduces modified additives into the core-shell structure, giving flexible stone excellent flexibility at -30°C, withstanding 100 freeze-thaw cycles without cracking or peeling, and weather resistance of 3500h. In maintenance of aging problems, the corresponding investigation direction is: if flexible stone shows chalking or cracking after 5–8 years of use, check whether product weather resistance reaches 2000h or above, and if necessary, locally replace with high-weather-resistance products using this technology.

The common pattern of the six major types of problems is: material problems focus on source acceptance, construction problems focus on standardized execution, design problems focus on node improvement, environmental problems focus on timely cleaning and waterproofing, usage problems focus on correct maintenance, and aging problems focus on regular testing and timely renovation. The essence of maintenance is not “repair only when broken,” but through classification judgment and cause tracing, transforming every maintenance into a basis for the next prevention.

26.2 Maintenance and Upkeep Plan

The maintenance and upkeep plan includes three levels: daily upkeep, regular inspection, and maintenance processes, forming a closed loop of “upkeep—inspection—maintenance—feedback.”

26.2.1 Daily Upkeep

Table 26-14 Daily Upkeep Plan

Daily upkeep focuses on routine cleaning and visual inspection, with low cost and simple operation, and is the most effective means of extending the service life of flexible stone. Key reminder: use neutral cleaners and soft tools during cleaning; strong acid or alkali cleaners, high-pressure water guns, and steel wool are prohibited.

26.2.2 Regular Inspection

Table 26-15 Regular Inspection Plan

Regular inspection is the core of proactive management. Bonding strength test results should meet ≥0.4 MPa, hollowing rate should meet ≤5%, and flatness should meet ≤3 mm. Inspection standards are consistent with the unified standards in Chapter 19. Inspection results should form written records as the original basis for maintenance decisions and aging trend judgment.

26.2.3 Maintenance Process

Table 26-16 Maintenance Process

Case: Three months after delivery of a project, the client reported local color differences in flexible stone. The maintenance process was: problem reception—response within 24 hours; on-site investigation—diagnosis within 48 hours, determined to be color difference caused by mixing different batches of materials; solution formulation—maintenance solution formulated within 72 hours; solution confirmation—confirmed with the client; maintenance implementation—remove color-difference areas, re-adhere with same-batch materials; acceptance feedback—feedback within 24 hours after completion, client confirmed satisfaction. This case shows that a standardized maintenance process is the core link of after-sales assurance; when the process is executed in place, maintenance quality can form stable expectations.

26.3 Maintenance Checklists

26.3.1 Daily Upkeep Checklist

Table 26-17 Daily Upkeep Checklist

26.3.2 Regular Inspection Record Form

Table 26-18 Regular Inspection Record Form

26.3.3 Problem Classification and Response

Table 26-19 Problem Classification and Response

The problem classification and response mechanism is the institutional guarantee for maintenance service efficiency. Level I problems involve personal safety and must be responded to immediately and handled within a time limit; Level II problems affect normal use and should be handled as soon as possible; Level III and IV problems can be included in planned maintenance. The purpose of classified management is to prioritize safety and function under limited maintenance resources.

26.4 Establishment of Maintenance Knowledge Base

The maintenance knowledge base includes three types of carriers:

Maintenance case library—problems, causes, treatment solutions, and lessons learned from each maintenance project;

Maintenance method library—standardized maintenance methods established for each type of problem;

Maintenance training materials—transforming maintenance cases and methods into training materials for maintenance personnel training.

Table 26-20 Maintenance Knowledge Base Architecture

The value of the knowledge base lies in “from individual cases to patterns”: after each maintenance is completed, the problem manifestation, cause judgment, treatment measures, and effect feedback should be entered into the case library; when similar problems accumulate to a certain number, they can be refined into standardized maintenance methods; methods are then transformed into training materials so that all maintenance personnel master the same standard. Through this cycle, maintenance experience can be precipitated from personal experience into organizational knowledge.

Decision Reference for Facade Retrofit Offices

I. Applicable Object Determination: This chapter applies to the operations and maintenance management of flexible stone facade retrofit projects after delivery, including maintenance response during the delivery warranty period and long-term maintenance outside the warranty period. Before decision-making, first determine the project stage: problems during the warranty period are the responsibility of the construction party, and those outside the warranty period are the responsibility of the owner or property management; then determine problem attribution by the six major types—material problems, construction problems, and design problems are mostly warranty-period responsibilities, while environmental problems, usage problems, and aging problems are mostly long-term maintenance responsibilities.

II. Key Decision Indicators: Daily upkeep once per quarter, regular inspection once per year, bonding strength testing once every 2 years; problem response is graded—Level I: 2-hour response, 24-hour processing; Level II: 24-hour response, 7-day processing; Level III: 48-hour response, 15-day processing; Level IV: 7-day response, 30-day processing. Maintenance acceptance standards are consistent with the unified standards in Chapter 19: bonding strength ≥0.4 MPa, hollowing rate ≤5%, flatness ≤3 mm.

III. Solution Comparison Recommendations: Maintenance solutions are selected according to the principle of “repair rather than replace where possible, local priority, overall fallback.” Small-area hollowing uses grouting treatment; larger hollowing uses local replacement; large-area hollowing requires reconstruction. Color difference problems prioritize local replacement with same-batch materials; overall replacement is used for severe color difference. Aging problems determine surface protection, local replacement, or overall renovation based on test results. Economic evaluation should adopt a full life cycle perspective, balancing maintenance cost with remaining service life, and avoiding the decision-making trap of saving money in the short term but spending more in the long term.

IV. Cost and Schedule Reference: Daily upkeep costs are relatively low, mainly cleaning labor and cleaner costs; regular inspection costs include testing fees for pull-off tests, water spray tests, etc.; maintenance costs increase with problem severity—grouting treatment is the lowest, local replacement is medium, and overall renovation is the highest. In terms of schedule, local maintenance can be organized by area, generally completed in 1–3 days; large-area renovation should be organized by zone, section, and off-peak periods to avoid affecting normal building use. Product protection and cleaning costs during maintenance should be included in the maintenance budget.

V. Implementation Risk Warnings: The three major risks are injury from detachment, substandard maintenance effects, and secondary damage during maintenance. Detachment risk—immediately set up warning areas for Level I problems to prevent personnel from approaching, and reinforce or remove after evaluation; substandard maintenance effects—acceptance after maintenance according to unified standards: bonding strength ≥0.4 MPa, hollowing rate ≤5%, flatness ≤3 mm; secondary damage—use neutral cleaners and soft tools for cleaning; high-pressure water guns, strong acids and alkalis, and steel wool are prohibited; maintenance operations should avoid damaging adjacent intact areas. All maintenance records should be archived and incorporated into the maintenance knowledge base.

Reflections on Stone, Insights on Fortune

Delivery of a facade retrofit project is not the endpoint; operations and maintenance is the starting point. The six major types, three plans, three checklists, and one knowledge base—this framework is not a system written on paper, but a standard that the maintenance team needs to truly execute. Classify problems clearly, set maintenance plans accurately, run response processes smoothly, and turn every maintenance into a basis for the next prevention; then operations and maintenance can move from passive to proactive. Making the client feel at ease relies not on oral promises, but on a complete operations and maintenance system that is executable, verifiable, and traceable.

References

[1] GB 50210—2018, Standard for Construction Quality Acceptance of Building Decoration[S].

[2] GB 50300—2013, Unified Standard for Constructional Quality Acceptance of Building Engineering[S].

[3] JGJ/T 29—2015, Specification for Construction and Acceptance of Building Painting[S].

[4] T/CECS 728—2020, Technical Standard for Comprehensive Renovation of Old Urban Residential Areas[S].

[5] Related general clauses in Chapters 15, 17, 18, and 19 of this book.