Constraints is an option in Primavera P6 to set the start or finish date regardless of the logic relationships. Since this option exists in P6 it means we can use it somehow. However, many consultants get confused when they found Constraints in the schedule, sometimes it is a must to use it.
When you should use Constraints in Primavera P6 Time Schedule:
Usually, you should use Constraints when there is scope of work to be done by others like the following:
- Handing over dates by others.
- Materials Delivery by others.
- NOC’s by others.
Additionally, we can use the Constraints to control the total floats where the project consists of several zones/stages. If one zone will be completed before the project date and there is no logical relationship with other zones, it might be a good idea to use finish Constraints to control the total float of this zone.
When you should NOT use Constraints in Primavera P6 Time Schedule:
Generally, you should not supersede a logical relationship with Constraints. Following are some examples of cases where you might think that Constraints is a good idea where it is not:
- Project Start / Finish dates.
- Important milestones Start/Finish dates.
- Testing and Commissioning Start date.
- Shop Drawings and Materials Start date.
Constraints are used for activities or events out of your control, you do not know how these activities happen, but you know when it will/should happen. Whatever under your control should be done in sequence without any imposing of start/finish to evaluate the forecast dates when doing progress update.