Autodesk 24000-000000-9860 - Revit Architecture - PC User Manual page 853

To cut an opening in a beam system
1 Select the beam system, and on the Options Bar, click Edit.
Sketch mode is active.
2 On the Design Bar, click Lines. Define the boundary of the opening.
3 Using the sketching tools available on the Options Bar, sketch a complete loop within the beam
system boundary.
Beam system boundary with sketched
opening
4 On the Design Bar, click Finish Sketch.
Beam system with opening
Creating a Structural Beam System | 815