Estimating Services


Quantity Takeoff Process

Services »Quantity Takeoff Process


In a construction estimating system the take-off starts from the original BIM or from an IFC file (or IFC data) exported from the original BIM and passed to the suitable designer to arrange the BIM for quantity take-off.


The entire exchange requirement in QTO inputs have been met once the BIM has been prepared for quantity take-off and validated.


The designer will now start to carry out a quantity take-off for cost estimate preparation. In estimating system reference data along with unit cost database and construction recipe database may be used as the estimating application.


At the time of review for quantity/cost analysis the consequence will be assessed directly from the QTO/Cost Review Report organized with a cost estimating system application. The result also may be verified by a BIM model checker using the IFC file with the results written back to it.


However in a estimating system if a quantity/cost analysis is performed , the results of the quantity/cost analysis is obtained and evaluated against any existing cost targets. If the targets are not achieved then the designer must make further modifications to the building geometry, constructions or some other building design variable. If the targets are achieved, the designer can move forward.

The situation occurs frequently where the designer is evaluating a given design not just against it costs, but also against other performance targets such as energy performance, circulation efficiency, etc. If a design meets the cost targets, but falls short of energy performance targets then the design can be ‘failed’ and designer will have to further iterate on the building design.


After receiving the IFC BIM complete with Quantity/Cost Report the client will use a data validation tool to verify that the BIM meets the requirement of the MVD.

The client may use internal staff or hire an outside consultant in an estimating system to verify the designer’s quantity/cost results. The estimating system application may use reference data such as Unit Cost Database and Construction Recipe Database to prepare the cost estimate.


The entire exchange requirement in QTO inputs have been met once the BIM has been prepared for quantity take-off and validated.


Once the quantity/cost analysis results in the estimating system are verified and approved, an analysis report is prepared comparing the results of the client’s analysis with those of the designer.

The client or consultants may insert URLs in the IFC BIM for the quantity and cost reports referencing the documents created in the quantity/cost analysis.


The client will evaluate the analysis report submitted by their internal staff or consultant. In the estimating system costs will be evaluated against the cost targets, resulting in a “go/no go” decision for the design.


The client will document the resulting quantities and cost analysis (which may or may not include an independent quantities and cost analysis for comparison/validation), and recommendations for the design team. The design feedback package will be delivered back to the designer, and will include either an approval or rejection of the design originally submitted to the client by the designer.


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