Soft Logic vs Hard Logic

Not all activity relationships are created equal. In project schedules, we distinguish between:

• Soft Logic (Flexible): Activities that can be executed in any order once the area is ready. Example: Light fittings vs. smoke detectors. Either can be installed first - there’s no mandatory dependency.

Another example is that you may prefer to work on Zone A first, then Zone B, but it is not mandatory to do so. Site conditions may require you to proceed in the opposite sequence.

• Hard Logic (Mandatory): Activities that must follow a strict sequence. Example: Block work → Plaster. You cannot plaster before the block work is complete.

Understanding the difference is critical.

• Soft logic gives flexibility in resource allocation and sequencing.

• Hard logic enforces the natural order of construction.

👉 Bottom line: Recognize which relationships are flexible and which are mandatory.

It helps you build realistic schedules and avoid costly mistakes.