A practical workflow for contractors to check quantities and handle design revisions in Qonic.
Architecture, structure, MEP and façades: four models, several formats and a deadline that has not moved. Somewhere in that information are the quantities your team needs to put a price on.
The finishes are missing, two concrete elements overlap and a revision arrives close to submission. You still need a take-off you can explain.
Qonic is browser-based BIM built around open IFC, with no specific hardware required. Its workflow for contractors lets you correct the model, measure the result and carry that work into the next revision. In the webinar From Models to Tender-Ready, Dieter Froyen and Jacob De Sutter showed how that works in practice.
Rewatch From Models to Tender-Ready on YouTube or see the whole workflow in 3 minutes:
Why design models need preparation
A design model reflects the scope and decisions of its author. It may omit finishes, contain intersecting elements or use classifications that differ from your estimating structure. Before you price from it, correct the information your take-off depends on.
A practical BIM tendering workflow
1. Combine the available design models
Bring the Revit, IFC, Rhino and SketchUp models into one project. Check units and model names, then set who can view or edit each model. Qonic uses IFC as its native data structure, so geometry and properties can be edited in the same environment used to inspect them.
2. Check alignment and project context
Confirm that architectural, structural and MEP models line up before measuring. Use known reference faces or objects to correct misplaced geometry. Sections and direct measurements help verify thicknesses, distances and clearances. Include site context where it affects logistics or the tender scope.
3. Prepare packages for suppliers
Separate the relevant elements into a focused model package, such as external windows for a joinery supplier. Set access rights for that model so the supplier can review and add to the information for their package, without access to the rest of the project.
4. Fill the gaps in the model
Decide how each missing item will be represented before calculating the final take-off. Some gaps require additional geometry; others can be handled through a documented estimating assumption.
Reinforcement without a rebar model. Multiply the concrete volume by an agreed reinforcement rate in kg/m³ to estimate rebar weight in kg. Store the formula as a dynamic property so it recalculates when its inputs change. Record the rate and its source alongside the result.
Missing plaster layers. Add the required finish geometry or model the relevant surfaces, then measure the area. Check how openings and wall connections affect the quantity.
Inconsistent family or type data. Use geometry matching to find repeated shapes even when names or type data are inconsistent. Check the specification and group the results into the packages you need to price.
5. Correct overlaps and organise the data
A slab and a wall can contain the same concrete where they intersect. Use clash detection to find the overlap, inspect it and correct the geometry where appropriate. Check the resulting volume before using it in the take-off.
Organise objects using your team’s classification or internal codes. Codes identify the items; measurement rules determine how their quantities are calculated. Use the net or gross quantities required by the tender.
6. Check quantities and structure the report
Calculate the count, length, area or volume required for each work package. Use visual quantity feedback to check which objects, faces and openings contribute to the result. For example, steel surface area can support an estimate for fire-resistant coating, while face selection can isolate glazing within a window assembly.
Group the results into a report that matches your estimating structure. Check the units and record the model version when you export, so the estimator knows which design the quantities represent. For a closer look at the reporting tools, see Quantity Take-Offs Made Easy.
7. Review the next design revision
When the revision arrives, upload the revised IFC file as a new version of the same model and choose Merge. Qonic combines the incoming changes with your clash corrections, codes and properties. Where edits conflict, you can choose which version of each change to keep. Compare the versions to see what was added, removed or modified and how the quantities changed.
In the webinar, the revised structural model had 16 wider columns. Qonic’s comparison showed what that meant: 0.53 m³ of extra concrete. The tender team could see which quantities needed repricing before updating the estimate.
The night before submission
Every tender team knows the moment: the total looks off, the deadline is tomorrow and nobody is sure which version the quantities came from. Keep the work in the model and that conversation gets a lot shorter.
→ Bring a real model and try it in your browser
Frequently asked questions
Can an incomplete BIM model be used for tender quantities?
Yes. Start with the available model, add missing geometry and record assumptions such as reinforcement rates. Check the resulting take-off against the scope you need to price.
How can I estimate rebar without a reinforcement model?
Multiply the relevant concrete volume by an agreed reinforcement rate. Store the calculation as a dynamic property to keep it connected to the model. Record the rate and its source so the estimated weight can be checked.
Will a new model revision overwrite my tender work?
Choose Merge when uploading a revised IFC file to the same model. Qonic combines the incoming design changes with your existing work and flags conflicting edits for review. Version comparison shows the quantity changes to check before updating the report.
How do Qonic quantities feed into my estimate?
Use Qonic to prepare the model and export a structured quantity report. Apply your rates and allowances in your estimating process. When the design changes, compare the model versions to identify the items that need repricing.
Check the quantity before you price it
Before pricing a package, you need to know what is included, what you have assumed and what changed in the latest revision. Keeping that work connected to the model makes it easier to check a total and explain it to the next person reviewing the tender.