Verification of Material Quantity Takeoffs from Building Information Models: Duplicate Elements, Revision Conflicts, and Procurement Consequences

Material quantity takeoffs can change because of model-processing errors rather than design changes. This paper develops a verification method for revision-aware material quantities, with explicit treatment of element identity, quantity meaning, units, and procurement allowances. A synthetic element ledger contains an approved 12 cubic meter revision of one wall and an 8 cubic meter second wall. The reference net quantity is 20 cubic meters. Summing a superseded revision increases it to 30 cubic meters; joining the current elements to repeated classifications increases it to 32. Under an illustrative 5% allowance and a price of 120 currency units per cubic meter, the revision error increases the calculated purchase amount by 1,260 currency units. Worked calculations and invariance checks establish these effects under the stated assumptions. The example operates on an extracted ledger and makes no claim of IFC parser performance or project savings. The contribution is an auditable quantity-verification procedure that distinguishes model quantities, revision selection, and procurement assumptions.