Direct Answer
Tekla Model Checker is an add-on tool (Trimble/Tekla) that runs automated checks on the structural model against a set of rules — detecting missing piece marks, unconnected members, duplicate parts, missing welds, geometry violations, and other common detailing errors before drawings are issued. Running the model checker before IFC package issue is a critical QC step that catches problems no human review reliably catches.
Full Explanation
Model Checker rule sets can verify: (1) All members have piece marks. (2) All members have at least one connection. (3) No duplicate assembly marks. (4) BOM weights are within expected ranges by section type. (5) All bolts are within allowable edge distances. (6) All welds have proper process assignments. (7) No clashing elements. Rules can be customized to project-specific requirements. Results appear as a report with each violation flagged and linked to the model element — the detailer clicks a flagged item and is taken directly to the problem in the model.
What This Means for Your Shop
Requiring your detailer to deliver a Model Checker report (zero critical violations) before issuing the IFC package is a contractual QC requirement that costs nothing extra and catches systemic detailing errors. Add it to your detailing contract.
Common Mistakes
Treating Model Checker as optional. Some detailers skip it to save time — the result is drawings with systematic errors (unconnected members, missing marks) that surface as RFIs and field problems.
Recommended Process
In your detailing contract, require delivery of a Model Checker clean report (or report with dispositions for all flagged items) as a pre-condition for issuing the IFC package. Review the report with the detailer before final IFC release.