Sequence Logic in Microsoft Project is the relationship that determines the order in which tasks are performed.
In simple words:
Sequence Logic = Which task must happen before or after another task.
Example: Building a House
| ID | Task | Logic |
|---|---|---|
| 1 | Excavate Foundation | Start First |
| 2 | Pour Concrete Footing | After Task 1 |
| 3 | Build Foundation Wall | After Task 2 |
| 4 | Backfill Soil | After Task 3 |
| 5 | Build Ground Floor Structure | After Task 4 |
Here the sequence is:
Excavate → Footing → Foundation Wall → Backfill → Structure
If Task 1 is delayed, all following tasks will be affected.
Why Sequence Logic is Important
1. Creates a Realistic Schedule
Without logic, all tasks may start on the same day.
❌ Wrong
Excavation
Foundation
Roofing
All start together.
✅ Correct
Excavation
Foundation
Columns
Beams
Roofing
2. Automatically Updates Schedule
If the foundation is delayed 3 days:
| Task | Before |
|---|---|
| Foundation | 10 May |
| Columns | 15 May |
After delay:
| Task | New Date |
|---|---|
| Foundation | 13 May |
| Columns | 18 May |
Microsoft Project automatically recalculates dates.
3. Identifies the Critical Path
Tasks connected by sequence logic create the schedule network.
Microsoft Project can then identify the:
Critical Tasks
Total Slack
Float
Project Completion Date
Types of Sequence Logic
1. Finish-to-Start (FS)
Most common.
Task B starts after Task A finishes.
Example:
Build Formwork
Pour Concrete
Logic:
Build Formwork FS Pour Concrete
Meaning:
Formwork must finish before concrete starts.
2. Start-to-Start (SS)
Task B starts when Task A starts.
Example:
Brickwork
Electrical Conduit Installation
Logic:
Brickwork SS Electrical Conduit
Both can start together.
3. Finish-to-Finish (FF)
Task B cannot finish until Task A finishes.
Example:
Painting
Final Inspection
Inspection finishes when painting finishes.
4. Start-to-Finish (SF)
Rarely used.
Task B cannot finish until Task A starts.
Example:
Old Security Guard
New Security Guard
Old guard finishes only after new guard starts.
How to Create Sequence Logic
Method 1: Predecessor Column
| Task | Predecessor |
|---|---|
| Foundation | |
| Column | 1 |
| Beam | 2 |
| Roof | 3 |
Microsoft Project automatically creates:
1 FS 2
2 FS 3
3 FS 4
Method 2: Link Tasks Button
Select multiple tasks
Go to Task tab
Click Link Tasks
Microsoft Project creates Finish-to-Start relationships automatically.
Construction Example
| ID | Activity | Predecessor |
|---|---|---|
| 1 | Site Clearing | |
| 2 | Excavation | 1 |
| 3 | Footing Concrete | 2 |
| 4 | Foundation Wall | 3 |
| 5 | Backfilling | 4 |
| 6 | Ground Floor Slab | 5 |
| 7 | Columns | 6 |
| 8 | Beams | 7 |
| 9 | Roof Structure | 8 |
This is the sequence logic network of the project.
Rule for Good Scheduling
A professional schedule should answer:
What to do? → Tasks (WBS)
Who will do it? → Resources
How long? → Duration
When? → Dates
In what order? → Sequence Logic
Without sequence logic, Microsoft Project becomes only a task list, not a true project schedule.
Construction Scheduling Formula
Project\ Schedule = Tasks + Durations + Sequence\ Logic
For your construction projects at 8AM Contractor, I recommend building the sequence in this order:
WBS → Duration → Sequence Logic → Resources → Baseline → Tracking
This produces a much more reliable schedule and helps Microsoft Project calculate the Critical Path correctly.