Network Voice (Cost Engineering Forum / Glodon User Group):
“The client insists on switching to Flexible Stone, but I’ve searched the entire local quota database and there’s no corresponding sub-item. I can only borrow the quota for ‘wall tiles’ or ‘stone’. As a result, the software’s default auxiliary material is cement mortar, but Flexible Stone requires a special flexible adhesive, which costs a lot more. The comprehensive unit price ends up being a loss.”
Network Voice (Project Manager at a General Contracting Group):
“We won the bid for a retrofit project based on the Flexible Stone quotation, but when we started scraping the wall, it was all sanding and hollowing. The design drawings didn’t include substrate treatment costs, and there’s no such item in the estimating software. Now the masons are demanding primers and repair mortar every day. We have to argue with the client for a variation order, and our profit is completely dragged out.”
Network Voice (Zhihu / Engineering Cost Community):
“Flexible Stone indeed saves the exterior wall dry-hanging keels and doesn’t need large tower cranes. But our preliminary/measure costs (措施费) were calculated based on traditional dry-hung stone. The scaffold and tower crane rental fees are saved, but the client demands to deduct this part of the measure costs directly. So the general contractor saves time and machinery, but gets no benefit at all.”
Network Voice (Overseas QS / Quantity Surveyor):
“Flexible stone seems cheap per square meter, but the substrate preparation and the specific flexible adhesive completely blow the budget. If we don’t price the substrate remediation as a separate BOQ item, the contractor will lose money.”
Analysis and Summary: Why Estimating Software Miscalculates Flexible Stone—Because Software Measures the “Surface,” While Flexible Stone Delivers a “System”
In the eyes of general contractors and quantity surveyors, the “miscalculation” of Flexible Stone is not a bug in the software itself, but a structural misalignment between the traditional Bill of Quantities (BOQ) pricing logic and the system delivery logic of Flexible Stone. Estimating software works based on “quota consumption” (定额消耗量); it is accustomed to the rigid mindset of “one tile + one bag of cement,” whereas Flexible Stone is a flexible system composed of substrate, adhesive, and joint sealing.
First Misalignment: Quota Sub-item Mismatch—Downgrading “System Thin-Set” to “Traditional Tile Laying.”
When quantity surveyors cannot find Flexible Stone in the software, their first reaction is to “borrow the wall tile quota.” However, the wall tile quota defaults to ordinary cement mortar or standard tile adhesive as auxiliary materials, and the labor is calculated based on the thick-bed method. Flexible Stone, on the other hand, requires “special flexible adhesive + notched trowel full-bed thin-set application.”
- Data Breakthrough: Ordinary cement mortar costs about 8 RMB/m², while the special flexible adhesive for Flexible Stone costs about 20 RMB/m². Thick-bed requires extensive on-site wet work and curing periods, while Flexible Stone is a dry, fast installation. If the auxiliary materials are not converted in the software, or if a supplementary quota is not separately compiled, the unit price calculated by the quota is bound to be “fake.”
Second Misalignment: Missing Hidden Costs—Retrofit Projects Cannot Be “Directly Applied.”
Estimating software likes to calculate “visible new surfaces,” but the fatal point of retrofits lies in the “invisible substrate.” The pain point of the general contractor in the network voice is very real: substrate removal, repair, primer application, and local leveling are often calculated as a one-size-fits-all area in traditional exterior wall renovations. But in the Flexible Stone system, these are critical processes that determine success or failure.
- Engineering Diagnosis: The “one trowel, two place, three press, four level” of Flexible Stone must be premised on substrate strength ≥ 0.3 MPa and moisture content ≤ 10%. If the original wall has sanding or hollowing, the repair and interface treatment costs must be listed as a separate item in the BOQ, and absolutely must not be lumped into the comprehensive unit price of Flexible Stone. Otherwise, work stoppages and disputes due to cost wrangling will be inevitable later.
Third Misalignment: The “Reverse Inversion” of Measure Costs and Schedule.
Traditional dry-hung stone or ceramic tiles require large tower cranes, long-term scaffold rental, and complex horizontal/vertical transportation. Flexible Stone weighs only 3–6 kg/m² and uses thin-set application, completely eliminating the need for heavy machinery, and the installation speed is 2–3 times that of ceramic tiles.
- Cost Logic: In the overseas QS (Quantity Surveying) system, the shortening of the schedule and the elimination of tower cranes mean a significant reduction in “time-related costs” and “site management fees.” If the contract does not adopt Life Cycle Cost (LCC) or Value Engineering, the client will only see that “the material unit price has increased” and then cut the saved measure costs. This results in the faster the general contractor works, the thinner their profit margin, and naturally, they have no incentive to promote it.
Breakthrough Suggestion: How to Make the Costing of Flexible Stone “Accurate”?
When delivering to general contractors and quantity surveyors, you cannot just provide a “material unit price.” You must provide a Structured BOQ:
- List “Substrate Diagnosis and Treatment Fees” as a separate item (priced by category based on actual conditions: direct application / local repair / system reconstruction);
- Clarify “Special Auxiliary Materials and Node Fees” (flexible adhesive, alkali-resistant primer, elastic sealant—none of which can be omitted);
- Calculate “Hidden Benefits” (eliminating structural reinforcement costs, tower crane rental fees, construction waste removal fees, and the capital recovery benefit brought by an earlier schedule).
Conclusion: Estimating software miscalculates because it does not understand the “system view” of Flexible Stone. As a material supplier and solution provider, only by making “hidden costs explicit and system processes itemized”—and transforming from a single “material supplier” into a consultant providing “Cost and Schedule Optimization Solutions (Value Engineering)”—can you completely eliminate the cost anxiety of general contractors and quantity surveyors.