Trade coordination and look-aheads

The contractor's schedule is updated once a month. Trades work by the day. Between the two sits the look-ahead: a short, detailed plan that turns next month's bars into this week's crews, materials and work areas. Owners rarely run look-aheads, but they can read them, and a project whose look-aheads are honest usually has a schedule that is honest too.

Learning outcomes

• Describe the planning levels between the master schedule and the daily huddle, and what each one is for.
• Read a three-week look-ahead derived from the contractor's schedule and spot activities that are not ready.
• Explain make-ready planning, the constraint log and Percent Plan Complete (PPC), and what PPC trends say.
• Identify the owner's own constraints in the look-ahead and act on them before they stop work.

The lesson

Why the monthly schedule is not enough

A good CPM schedule shows logic, float and the critical path. It is updated monthly, as lesson 13 on schedule updates explains, and its activities are usually a week or more long and cover a whole area. That is the right level for forecasting completion. It is the wrong level for deciding which crew goes to which gridline on Tuesday. Trade coordination needs a plan that is shorter, more detailed and updated every week.

Planning levels

The Last Planner System, developed by Glenn Ballard and Greg Howell in the 1990s and promoted by the Lean Construction Institute they founded, organizes this into levels. Each level plans in more detail as the work gets closer. The people who plan the bottom levels are the "last planners": the foremen and superintendents who commit their crews. Figure 1 shows the levels with their usual horizons.

The look-ahead

A look-ahead starts from the current CPM schedule. The superintendent filters the activities that start or continue in the next three to six weeks, then breaks each one into the pieces crews actually do: by area, by floor, by sequence. A schedule bar called "roofing" becomes membrane in areas A and B this week and area C next week. The look-ahead should never contradict the CPM schedule. If the field plan has moved away from the logic, the next schedule update has to catch up, or the critical path in the monthly report is fiction.

On a CCDC 2 project the contractor controls means, methods and sequencing, and under Ontario's OHSA the constructor coordinates the trades for safety, as lesson 6 on owner and constructor duties explains. So the look-ahead belongs to the contractor. The owner reads it, asks questions and removes the owner's own constraints. The owner does not direct trades.

Make-ready and the constraint log

The purpose of looking ahead is to make work ready before it is due. For each activity in the window, the team asks what could stop it: unfinished predecessor work, missing design information or an open RFI, materials not delivered, labour, equipment, space and access, and approvals or inspections. Each constraint goes in a log with an owner and a date it must be cleared. The rule at the bottom level is strict: an activity goes into the weekly work plan only when its constraints are cleared. A plan full of work that cannot start is a wish list.

Many constraints belong to the owner's side: Consultant answers to RFIs (lesson 9 covers RFI turnaround), submittal reviews, owner decisions, owner-supplied items, utility connections and the owner's separate contractors. These are the lines the owner's representative should read first.

The weekly coordination meeting

The trade coordination meeting is the contractor's meeting with its foremen, separate from the OAC meeting. A sound agenda runs in this order: safety; last week's commitments, kept or not, and why; next week's commitments by trade; the look-ahead and constraint log; area handoffs between trades; logistics such as cranes, lifts, laydown and deliveries. It should take about an hour. The owner's representative may attend as an observer, and the contractor should report its outputs at the OAC meeting.

Percent Plan Complete

PPC is the share of last week's commitments that were completed as promised. Twenty commitments with fifteen kept is 75%. Partly finished work earns no credit. The value of PPC is less in the number than in the reasons recorded for each miss. Mastt's summary cites Lean Construction Institute figures that only about 54% of planned weekly work typically gets done, treats 70% as a reasonable target, and warns that a PPC held in the high 80s may mean crews are committing to too little. A rising PPC with the same reason repeating, such as "materials", points to a procurement problem, not a field one. Because PPC only looks backward, some teams also track the share of constraints removed by their due date, a leading measure proposed by Jang and Kim at the 2007 International Group for Lean Construction conference.

Northgate worked example

Northgate Distribution Centre (fictional) is a 12,000 m² tilt-up warehouse in Vaughan, with Halvorsen Builders Ltd. (fictional) as contractor under CCDC 2-2020 and Ridgeline Architects Inc. (fictional) as Consultant. By early August 2027 the panels are up (M5, June 25) and the team is driving to M6, roof complete and weathertight, on Friday September 3. Halvorsen's Oracle Primavera P6 schedule shows broad activities for roofing, fire protection and electrical; the owner's master schedule in Microsoft Project carries only the milestones. See the Northgate fact sheet.

The three-week look-ahead

Halvorsen issues its look-ahead every Monday. Figure 2 shows the one issued on August 2 for the weeks of August 9, 16 and 23. Four of the eight activities carry an open constraint.

View the data

Activity	Start	Finish	Open constraint
Roof deck, area C	Mon Aug 9	Fri Aug 13	None
Roof membrane, areas A-B	Wed Aug 11	Fri Aug 27	Roof inspection to be booked
ESFR mains, areas A-B	Mon Aug 9	Fri Aug 20	None
ESFR branch lines, area A	Mon Aug 16	Fri Aug 27	RFI on sprinkler and light conflict
High-bay lights, area A	Mon Aug 23	Fri Aug 27	Branch lines; owner's racking layout
Switchboard set and terminate	Mon Aug 23	Fri Aug 27	Delivery Mon Aug 16
Dock levellers, docks 1-7	Mon Aug 16	Wed Aug 25	None
Mezzanine stud framing	Mon Aug 9	Fri Aug 20	None

The owner's representative reads the constraint column first and finds two items on the owner's side. The RFI on the conflict between ESFR branch lines and high-bay lights is with Ridgeline and its engineers; it needs an answer by August 13 or the branch lines in area A slip. The high-bay lights also depend on the final racking layout from the owner's racking supplier, because fixtures are aligned with the aisles. Neither item is on Halvorsen's critical path yet, but both feed the commissioning sequence after M7. The owner's representative chases both at that week's OAC meeting and records the dates in the minutes. The switchboard constraint is the delivery tracked in the procurement log from lesson 18.

Reading the PPC trend

Halvorsen reports PPC weekly. Figure 3 shows eight weeks from early July to August 20.

View the data

Week ending (2027)	PPC
Fri Jul 2	58%
Fri Jul 9	62%
Fri Jul 16	55%
Fri Jul 23	66%
Fri Jul 30	71%
Fri Aug 6	64%
Fri Aug 13	73%
Fri Aug 20	76%

The trend is upward, which suggests the make-ready process is working. The reasons for variance over the same eight weeks tell the owner where to look next.

Six misses traced to design information is the owner's share. That is enough for the owner's representative to ask Ridgeline for a standing RFI review slot until roof and fire protection are done.

Owner's move

• Require the look-ahead and constraint log as deliverables. Specify weekly issue in Division 01, with the constraint owner and clear-by date on each line.
• Read the owner's constraints first. RFIs, submittals, owner decisions, owner-supplied items, utilities and separate contractors are yours to clear.
• Check the look-ahead against the CPM schedule. If the field sequence has moved, ask for it to be reflected in the next update.
• Ask for PPC with reasons, not PPC alone. The reasons tell you whether the problem is in the field, the supply chain or the design team.
• Observe, do not direct. Attend the coordination meeting occasionally, but route instructions through the contract.

Common mistakes

1. A look-ahead that is just the CPM schedule reprinted. Without area and crew detail it cannot show what is ready.
2. Putting constrained work in the weekly plan. Crews arrive to work they cannot do, and PPC collapses.
3. Using PPC to blame trades. It is a learning measure; used as a stick, it teaches crews to under-commit.
4. Letting the field sequence drift from the schedule. The monthly update then reports a critical path nobody is following.
5. Owner directing trades at the coordination meeting. It blurs who controls the Work and who is the constructor.

Quick quiz

1. Which planning level is mainly used to find and remove constraints?

   1. Master schedule
   2. Look-ahead
   3. Daily huddle
   4. Baseline

2. A crew made 20 commitments last week and completed 14, with 3 more half done. What is PPC?

   1. 70%
   2. 78%
   3. 85%
   4. 100%

3. Under the Last Planner System, when does an activity go into the weekly work plan?

   1. When it appears in the CPM schedule
   2. When its constraints are cleared
   3. When the owner approves it
   4. When float runs out

4. On Northgate, which constraint belongs to the owner's side?

   1. Roof deck in area C
   2. Mezzanine stud framing
   3. The racking layout needed to set high-bay lights
   4. Dock leveller installation

5. What might a PPC held at 92% for months suggest?

   1. A perfect project
   2. Crews committing to too little
   3. The schedule is late
   4. Too many RFIs

Show answers and explanations

1. B. The look-ahead is the make-ready window, where constraints are logged and cleared.
2. A. 14 of 20 is 70%. Partly finished commitments earn no credit.
3. B. Only ready work goes in, so commitments can be kept.
4. C. The racking layout comes from the owner's separate racking supplier, so clearing it is the owner's job.
5. B. A very high, steady PPC often means the team is under-committing to protect the number.

Key terms

Look-ahead schedule

A short-horizon plan, usually three to six weeks, that breaks schedule activities into crew-level work and is updated weekly.

Last Planner System

A production planning method developed by Ballard and Howell in which the people who commit crews plan the near-term work.

Make-ready

Identifying and removing constraints so that work is ready when it is due.

Constraint log

A list of what could stop each look-ahead activity, with an owner and a clear-by date.

Weekly work plan

The commitments each trade makes for the coming week, limited to ready work.

Percent Plan Complete (PPC)

Commitments completed as promised divided by commitments made, for one week.

Reasons for variance

The recorded cause of each missed commitment, used to fix the system rather than blame crews.

References

1. Mastt, Last Planner System: the 5 levels, PPC and what makes it work.
2. Designing Buildings Wiki, Last Planner System.
3. J. W. Jang and Y.-W. Kim, Use of percent of constraint removal to measure the make ready process, IGLC 15, East Lansing (2007).

Verified on November 6, 2026.

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