The definition of preliminaries and its two charging bases: measurable preliminaries (priced like divisional-work costs) and comprehensively charged preliminaries (a rate on divisional-work costs plus measurable preliminaries)

Topic Positioning

The definition of preliminaries and the difference between the "measurable" and "comprehensively charged" bases at budget stage, centring on the percentage base formula.

Core Conclusions

1) Definition (GB/T 50500-2024 clause 2.0.3). Preliminaries - "items of a technical, welfare, work-safety or environmental-protection nature arising in construction preparation, construction and acceptance for completing the works; their costs are the preliminaries cost." The term further bounds it: costs "of measures taken to perform the contract, tied to the works cost as a whole and to contract-performance costs, but not to the costs of individual divisional-work items." The test: tied to the whole and to performance - not to any divisional item.

2) The two bases (GB/T 51095-2015 clause 5.3.10). Building-works budget preliminaries compute as follows:

• Item 1: "measurable preliminaries price by the same method as divisional-work costs, per clauses 5.3.8 and 5.3.9."
• Item 2: "comprehensively charged preliminaries compute as the sum of the unit work's divisional-work costs and measurable preliminaries, times the applicable rate." The clause restates: "of the preliminaries in a building-works budget, the measurable part prices by reference to the divisional-work method, and the comprehensively charged part takes the unit work's divisional-work costs plus measurable preliminaries as base, times the rate."

3) The same basis locally (DB42/T 823-2021 clause 6.3.10). Identical content, citing "clauses 6.3.8 and 6.3.9 of this document": a) measurable preliminaries price as divisional-work costs; b) comprehensively charged preliminaries = (divisional-work costs + measurable preliminaries) x the rate.

4) Pricing-mode classes. GB/T 50500-2024 drops the old "unit-price / lump-sum preliminaries" pair, classifying instead by unit-price, lump-sum and percentage modes; lump-sum pricing is preferred for preliminaries (clause 3.2.1); lump-sum preliminaries lock the price and generally do not re-measure (clause 7.3.1 lists the exceptions), unit-price preliminaries move with quantity.

5) Recomputation at settlement (GB/T 50500-2024 clause 10.3.3). "At final account the parties shall recompute the preliminaries and main contractor's attendance listed in interim settlement documents ... 1 the preliminaries compute per section 7.3 and chapter 8 as the full preliminaries contained in the completed works, including adjustments to the statutory work-safety provisions. Preliminaries listed in interim settlements do not bind the final account." The final figure is the recomputed one; interim listings are no basis.

Applicability Boundaries

• Clause 5.3.10 governs the design (budget) stage; the "applicable rate" comes from the companion on-cost quota and the current local pricing basis and must match the compiling-period rate - never assumed.
• Measurable preliminaries are those whose quantities the measurement rules can compute (design-shown dimensions), priced by the divisional-work method (quota items, labour / materials / plant / overheads / profit); percentage charging suits what physical quantity cannot compute - the two never double-charge one content.
• The percentage base is "the unit work's divisional-work costs + measurable preliminaries", excluding the percentage part itself - never divisional-work costs alone, never stacked level upon level.
• Railway, highway and other systems run their own bases (railway construction-measure cost = (base-period labour + base-period plant) x the rate) - never mix with this percentage basis.

Further Reading

• GB/T 50500-2024 Standard for Pricing of Works on a Bill of Quantities Basis, clauses 2.0.3, 2.0.10, 3.2.1, 7.3.1 and 10.3.3.
• GB/T 51095-2015 Code for Construction Cost Consultation, clause 5.3.10 and the cited 5.3.8, 5.3.9.
• DB42/T 823-2021 Code for Quality Control of Construction Cost Consultation, clause 6.3.10 and the cited 6.3.8, 6.3.9.
• Sector comparison: TB 10801-2024 Measures for Compiling Railway Estimates, section 3.6 (rates per TB 10811); highway per JTG 3830-2018 section 3.1 (base = quota labour + quota plant).