What is a Revit ʼConstraintʼ (the padlock icon)?
Short Answer
A revit constraint is a relationship lock shown by the padlock icon that keeps elements aligned or dimensioned together. The most common professional method is using Align to line up geometry, then clicking the padlock to lock that relationship. A key limitation is that over-constraining a model can cause edit failures.
What You Need to Know Before
Warning: Locked constraints can silently create conflicts when walls, grids, levels, or hosted families are edited later. A very common failure is a “Constraints are not satisfied” warning after moving one element that is locked to multiple references.
How to Create and Use a Revit Constraint
Command: ALIGN
Shortcut: AL
Quick Steps:
- On the Ribbon > Modify panel, click Align.
- Select the reference element first, then select the element face, line, or reference plane you want to align.
- After alignment, click the padlock icon that appears to lock the constraint.
Use the fastest common method: align first, then lock.
Real option: enable Multiple Alignment on the Options Bar if you need to align several elements to the same reference.
Variables & Settings
Key Setting: Multiple Alignment toggle in the Options Bar
Expert Setting: When enabled, Revit keeps the Align command active so you can apply the same reference to several elements quickly. This speeds up layout work, but locking too many items to one reference can make later edits harder.
Why it Fails
- Cause 1 (Geometry): The elements do not share valid parallel or matching references, so Revit cannot create a stable locked alignment.
- Cause 2 (layers/Locks): The element is already pinned, hosted, or constrained to another object, creating a conflict with the new padlock constraint.
- Cause 3 (Command/Logic): Too many constraints exist in the same area, so moving or editing one object makes the constraint set unsatisfiable.
Quick Fix & Best Practice
- Quick Fix: Use Reveal Constraints from the view control Bar, identify the conflicting lock, and delete or unlock the extra constraint before editing.
- Manager’s Verdict: Use padlock constraints for critical design intent like grids, centerlines, and controlled family behavior. Avoid locking everything, especially in repetitive production models where flexibility matters more than rigid control.
FAQ
How do I remove a Revit constraint?
Select the locked element or dimension, then click the padlock to unlock it or delete the constraining dimension.
Is a Revit constraint the same as pinning?
No, pinning prevents movement of one element, while a constraint controls the relationship between elements.
Why does Revit say constraints are not satisfied?
It usually means one element is locked to multiple references that no longer agree after a change.
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