Navisworks quantity takeoff: from combined models to a checkable BOQ
Navisworks quantity takeoff brings information from several models into one workbook, while each quantity still needs a clear source and a defined purpose. Before totals are assigned to concrete, finishes or building services, the team needs to know which model governs each work item, which properties were exported and which parts remain unresolved. A useful bill of quantities connects those decisions to locations and measurement rules, so a contractor or project owner can review how the figures were obtained.
Navisworks quantity takeoff starts with the source package
A combined model can help a quantity surveyor review several disciplines together. It also brings together information prepared for different purposes. The initial package should therefore identify each file, its revision, its discipline and the area it covers. A file name alone does not establish that a model is the current measurement source.
Autodesk provides Quantification in Navisworks Manage and Navisworks Simulate. Check the installed edition and version before agreeing a workflow; opening a model in a viewer does not establish that takeoff tools are available. Product information is on Autodesk's Navisworks page. Autodesk and Navisworks are their owner's trademarks. This website is independent of the vendor.
The next check is a small sample of actual elements. Can the relevant properties be read, do they carry the expected units, and can the elements be traced to the source documents? A visible shape may support a visual review while still lacking the information required for the requested takeoff.
Keep model, virtual and sheet takeoffs identifiable
Model takeoff uses the properties and object identifiers exported from the authoring application. Those inputs must be retained and mapped appropriately. When required information is missing, review the export before treating the model as a source for the work item. A large selection also needs a scope check: the selected group may include elements outside the intended quantity.
Virtual takeoff provides a separate entry for work that is not linked to a suitable model object. A calculation and an associated viewpoint can help explain it. Such an entry does not refresh from the model, so its supporting drawing or specification and its review status need to remain visible.
For supported 2D sheets, including PDF, lengths, areas and counts can be marked on the drawing. Check the scale against a known dimension and identify the sheet revision. A sheet markup does not acquire model element properties simply because it sits beside a 3D takeoff in the same workbook. Record what it covers and check that the same work has not already been counted elsewhere.
A model property needs a measurement rule
An area field is not a complete definition of a finish, and a component volume does not describe every operation required to build it. Establish what each value represents, which unit applies and whether it matches the project's method of measurement. The related guide to quantities from a Revit model explains further source-model checks.
The item catalog organises takeoff entries and their property mappings and formulas. Its structure should match the work being measured. Before applying a rule to a large group, check a representative element and an exception, such as a wall with an opening or a surface with a partial finish. A missing value remains a query; it does not become zero.
Check coverage and duplicates before trusting a total
Agree a source for each work type, then keep that decision consistent. Review overlapping elements, areas omitted from selections and entries repeated across files. A workbook can add its rows correctly and still describe an incomplete selection. Compare its coverage with the drawings and specifications before relying on the summary.
| Check | Question | Record |
|---|---|---|
| Quantity source | Which model and revision govern this work item? | File, scope and any alternative source excluded |
| Selection coverage | Are the required floors and areas included? | Location breakdown and areas still to be reviewed |
| Property and unit | Does the field represent the specified work? | Field, calculation rule and explained deductions |
| Supplementary work | What is absent from the model? | Drawing or specification, calculation and query status |
Ratios and comparisons can identify places worth investigating. A difference between similar floors may reflect a change of finish, an omitted area or a selection error. Check the reason before copying a quantity from one floor to another. The guide to quantity cross-checks describes the broader review approach.
Make the handover traceable to the work
A useful handover includes the work description, unit, location breakdown and a calculation that can be followed back to its source. Depending on the agreed scope, it can also identify elements or groups, file revisions and the basis of additions and deductions. Quantities taken from the model should remain distinguishable from quantities calculated separately.
Exporting to Excel is a step in that handover. Check the exported totals against the Quantification workbook, verify units and confirm that filters have not hidden required rows. The quantity calculation file should then be arranged around the project's intended use. A tender, a material order and a review of completed work may need different breakdowns. Specify that detail when the service is scoped.
A revision needs a reviewed explanation of the change
Retain the earlier calculation basis when a new model revision arrives. Change Analysis helps compare property changes for review; the quantity surveyor still needs to decide what they mean for the BOQ. Check whether the selection or the meaning of a field changed as well as whether its value increased or decreased. Review virtual entries and sheet markups against their own supporting sources.
Navisworks quantity takeoff is ready for a documented handover when the update and the outstanding queries can be explained. To discuss a project, provide the model list, relevant drawings and specifications, requested work sections and intended deliverable. I work as a quantity surveyor and registered building technician in Israel, measuring from the perspective of the contractor carrying out the work. Pricing or an estimate is an additional service agreed separately with the client; verbal feedback on costs is not a commitment to a construction price.
Frequently asked questions
Does a model that opens in Navisworks necessarily support the requested takeoff?
No. Check which properties and identifiers survived the export and how they can be mapped to the required work items. Geometry that can be viewed does not prove that every relevant quantity is available.
Can model quantities be combined with quantities from drawings?
Yes, when their sources and scopes remain identifiable. Before adding them together, check that a supplementary drawing quantity does not repeat work already included in the model takeoff.
Does virtual takeoff update automatically with the model?
No. It is not linked to model refresh. For each revision, review its supporting source, formula and whether the entry needs to be changed or removed.
What should be supplied to define the service?
Provide the file and revision list, models with their available data, relevant drawings and specifications, requested work sections and the purpose of the handover. Identify missing information so the measurable scope and required supplements can be agreed.
* Created with AI for marketing, for illustration only. Not reviewed by Yaakov Avital and not professional advice. Every project must be checked on its own by a professional quantity surveyor and an engineer.