Most construction schedules are built in an office by a scheduler and a project manager, then handed to the trades. The trades look at it, decide privately which dates are real, and plan their own work around what they think will actually happen. The schedule and the site drift apart, and by the third month the monthly update is more fiction than plan.
The Last Planner System was developed to close that gap. It asks the people who actually do the work to plan it, make promises to each other, and measure whether those promises were kept. This guide explains the system as a whole, how a pull planning session works, what Percent Plan Complete tells you, and where the owner fits in. Our separate guide to three-week look-ahead schedules covers the look-ahead step in detail.
Where Last Planner came from
The Last Planner System is closely associated with Glenn Ballard and the Lean Construction Institute, which holds "Last Planner" as a registered trademark. Ballard's 2000 PhD thesis at the University of Birmingham set out the system as a method of production control, designed to make sure plans are carried out rather than simply detecting variances after the fact.
The name comes from the idea of the "last planner": the person who directly supervises the work and decides what a crew will do tomorrow. On a general contractor's team that may be an area superintendent. For a trade contractor, it's usually the foreman. The system's premise is that these people make the most reliable plans because they know what's actually possible.
Should, can, will, did
A simple way to understand the system is through four questions. Conventional scheduling focuses on what should be done to meet the milestones. Last Planner adds what can be done, because the prerequisites are in place, and what the team will commit to doing. Then it checks what they did, and asks what can be learned from the difference.
The gap between should and can is where most delays come from. Work that should start this week often can't, because a drawing isn't approved, materials haven't arrived or the area isn't ready. Traditional scheduling pushes the work anyway, and the crew either stands around or works out of sequence. Last Planner pulls the work forward only once the constraints are cleared.
The five levels of the system
The Lean Construction Institute's workbook describes a set of connected planning levels, each with more detail and a shorter horizon than the one above it.
- Master or milestone schedule. The overall project plan, typically a CPM schedule, setting key milestones and the overall duration.
- Phase schedule, built through pull planning. Each major phase, such as structure, envelope or interiors, is planned collaboratively by the trades who'll do it, working backward from the phase milestone.
- Look-ahead and make-ready planning. A rolling window of the next several weeks, typically around five to six according to the LCI workbook, where constraints are identified and removed so work is ready to start.
- Weekly work planning. Each last planner commits to specific tasks for the coming week, but only tasks that are well defined, sound, in the right sequence and properly sized.
- Learning. Every missed commitment is recorded with a reason, and the team looks for root causes so the same failure doesn't repeat. Daily huddles keep the weekly plan on track in between.
View the data
| Question | Level | Horizon and purpose |
|---|---|---|
| Should | Master / milestone schedule | Whole project · CPM milestones |
| Should | Phase schedule (pull planning) | Each phase · trades plan backward |
| Can | Look-ahead / make-ready | About 5–6 weeks · remove constraints |
| Will | Weekly work plan | Next week · reliable commitments |
| Did · Learn | Learning | PPC and reasons for variance |
The levels are meant to work together. The master schedule sets the targets. Pull planning turns those targets into a realistic sequence. The look-ahead makes the work ready. The weekly plan commits to it. Learning improves the next round.
How a pull planning session works
Pull planning is the most visible part of the system, and the part owners are most likely to be invited to. The basic method:
- Start at the milestone. The team picks a phase milestone, such as building enclosed or level 2 ready for ceilings, and puts it on the right-hand side of a wall.
- Work backward. Each trade asks: what do I need to have done, and by whom, before I can do my work? Tasks go up on sticky notes, one colour per trade, placed in sequence from the milestone back to today.
- Focus on handoffs. The conversation is about what each trade needs to release to the next one. Those handoffs become the control points.
- Use honest durations. The LCI workbook calls for durations without padding, then a review of the logic to find ways to shorten the plan.
- Allocate the buffer deliberately. If the backward plan fits with time to spare, the team decides where to put that buffer, typically on the most uncertain tasks, rather than letting it disappear.
The key is who's in the room. Construction Dive's reporting on pull planning quoted one contractor's lean specialist on the point: they want "the person responsible for executing the work." A project manager who's never run a crew can't make a reliable promise about how long rough-in will take on a congested floor.
The output is a phase schedule that the trades actually believe, because they built it. It should then be reconciled with the CPM master schedule. If the pull plan says the phase takes longer than the master schedule allows, that's a conversation to have now, not in month six.
Percent Plan Complete
Percent Plan Complete, or PPC, is the system's main measure. It's the number of weekly commitments completed divided by the number made. A task is either done or not done. There's no partial credit, because a half-finished task doesn't release the next trade.
PPC measures reliability, not progress. A team that commits to ten tasks and completes eight has a PPC of 80%, whether those tasks were big or small. That's the point. Reliable promises are what let the next trade plan its crew.
Ballard's thesis notes that earlier research had linked reaching a PPC of about 70% with substantial productivity gains, and its final case study reached a 90% target. On programs we've supported, teams new to the system often start well below 70% and improve as constraints get managed earlier and commitments get more realistic.
View the data
| Week | PPC |
|---|---|
| 1 | 48% |
| 2 | 55% |
| 3 | 52% |
| 4 | 61% |
| 5 | 64% |
| 6 | 58% |
| 7 | 68% |
| 8 | 72% |
| 9 | 70% |
| 10 | 76% |
| 11 | 79% |
| 12 | 82% |
The reasons for missed commitments matter more than the number. If PPC is low because RFIs aren't answered, that's a design team or owner issue. If it's because materials are late, that's procurement. Tracking reasons over time shows where the system is failing.
The owner's role
Last Planner is often described as a contractor's tool, and day to day it is. But owners affect it more than they realize, and a few things are worth doing deliberately.
- Show up to the pull sessions that matter. Owners are commonly among the stakeholders invited to pull planning, alongside designers and suppliers. Attend the ones where owner decisions are on the path: design approvals, owner-supplied equipment, tenant requirements, permits and turnover.
- Make your own promises reliable. Owner tasks, such as approving finishes, delivering furniture or connecting IT, belong on the wall like anyone else's. If you commit to a decision date, keep it. An owner who misses commitments teaches everyone else that the plan is optional.
- Answer RFIs and submittals fast. These are the most common owner-side constraints in the make-ready process.
- Don't use PPC as a stick. If low PPC triggers penalties, teams will commit to less and hit 100% of very little. Use it as a diagnostic and ask about the reasons.
- Keep the CPM schedule. Last Planner doesn't replace a sound baseline or the contractual schedule. It makes the baseline achievable. Owners still need a locked baseline for measuring progress and assessing delay.
When it works and when it doesn't
Last Planner works best on projects with many trades working in close sequence, such as interiors, healthcare, labs and occupied renovations, where handoffs drive the schedule. It's also valuable on multi-site programs, where the same trades repeat similar sequences and learning carries from site to site.
It struggles when the trades' decision-makers don't attend, when the general contractor runs it as a reporting exercise rather than a conversation, or when the contract structure gives trades no reason to cooperate. Under a stipulated price contract the system still helps, but owners shouldn't expect the collaboration they'd see under integrated or construction management arrangements unless the contractor buys in.
What owners should do
- Ask at the interview stage whether the contractor uses Last Planner or pull planning, and ask to see a recent PPC chart with reasons for variance.
- Require pull planning for key phases in the contract or execution plan, with the outputs reconciled to the CPM schedule.
- Put owner tasks on the wall, and assign an owner representative who can make and keep commitments.
- Read the reasons, not just the PPC, and act quickly on any that point at the owner or design team.
- Keep the baseline and the contractual schedule as the record for progress and delay, with Last Planner as the tool for hitting it.
The bottom line
The Last Planner System replaces a schedule handed down from the office with commitments made by the people doing the work, and then measures whether they were kept. For owners, it's one of the most practical ways to get a schedule the site believes. The owner's job is to show up, keep its own promises, and treat PPC as a signal rather than a scorecard.
Want help introducing pull planning or reviewing how it's working on your project? Book a 30-minute call with Benjamin R. Consulting.
Sources: Ballard, H.G., The Last Planner System of Production Control, PhD thesis, University of Birmingham (2000); Lean Construction Institute, Last Planner System Workbook; Lean Construction Institute, Last Planner System Standard Work: Introduction and Principles; Construction Dive, How pull planning can streamline project schedules, encourage collaboration (2017). Last Planner and Last Planner System are registered trademarks of the Lean Construction Institute. The PPC chart is illustrative. This article is general information, not legal advice.