- What lean construction is
- Visual map of pull planning on site
- Why a building site needs a different planning method
- The 4 Last Planner horizons
- Lookahead and constraint removal
- PPC: the plan reliability measure
- Worked example: 4 weeks on a building project
- Weekly routine
- Beyond the Last Planner System
- Common mistakes
- Frequently asked questions
What lean construction is
Lean construction applies the principles of lean manufacturing to building projects: reduce waste, stabilize work flow between trades and deliver value to the client. Its best-known planning tool is the Last Planner System, which turns the project schedule into reliable weekly commitments.
The theoretical base comes from Lauri Koskela, who in 1992 proposed viewing construction as a flow and not only as a conversion of inputs into a product. The Last Planner System was developed by Glenn Ballard and Greg Howell, associated with the Lean Construction Institute.
Visual map of pull planning on site
The map shows the 4 planning horizons, the 6-week lookahead and the PPC calculation from the example.
Why a building site needs a different planning method
A traditional schedule pushes activities by date: if the flooring crew is scheduled for Monday, it arrives, even if the substrate is not released or the material has not been delivered. The result is waiting, rework and work done out of sequence.
The Last Planner System reverses the logic. Instead of asking "what is on the schedule this week?", it asks "what can be done?" Crews commit only to tasks with no open constraint. It is the same reasoning as pull production: work is released by what is ready to receive it.
The 4 Last Planner horizons
| Horizon | Span | Question | Output |
|---|---|---|---|
| 1. Master schedule | Whole project | What are the milestones? | Delivery dates and phases |
| 2. Phase (pull) planning | One phase | What does each trade need to receive from the previous one? | Agreed sequence and durations, planned backward |
| 3. Lookahead | 6 weeks, updated weekly | What must be free for the work to be doable? | Constraints identified and removed |
| 4. Weekly work plan | 1 week | What will we actually do? | Commitments and PPC measurement |
In phase planning, the trades stick cards on a wall starting from the handover date and working backward. The people who do the work set the duration and what they need to receive, which creates real commitment.
Lookahead and constraint removal
The lookahead covers the next 6 weeks and asks the same question for every activity: is it ready to be executed? Typical constraints:
- Design: missing detail, a question answered only through an RFI.
- Material: order without a confirmed delivery date.
- Labor and equipment: crew or machine still allocated to another area.
- Space: predecessor not finished or area not released.
- Safety and permits: approvals and scaffolding in place.
Each constraint gets an owner and a deadline in an action plan such as 5W2H. Only activities that are free of constraints move into the weekly plan.
PPC: the plan reliability measure
PPC = tasks completed ÷ tasks planned for the week × 100
A task counts as complete only if it was 100% finished; 90% done scores zero. PPC measures whether crews keep their promises, not productivity.
Worked example: 4 weeks on a building project
Fictional example. The team recorded the tasks in the weekly work plan and the ones completed:
| Week | Planned | Completed | PPC |
|---|---|---|---|
| 1 | 20 | 15 | 75.0% |
| 2 | 18 | 14 | 77.8% |
| 3 | 22 | 19 | 86.4% |
| 4 | 20 | 18 | 90.0% |
| Total | 80 | 66 | 82.5% |
Each of the 14 incomplete tasks was given a recorded cause:
| Cause | Tasks | % of failures |
|---|---|---|
| Material did not arrive | 5 | 35.7% |
| Crew or equipment unavailable | 3 | 21.4% |
| Incomplete design or open question | 3 | 21.4% |
| Rain | 2 | 14.3% |
| Predecessor late | 1 | 7.1% |
Material and labor account for 8 of the 14 failures (57.1%). The action sits in the lookahead: confirm deliveries and allocations 3 to 4 weeks ahead. This is a Pareto analysis applied to a building site. After any week of low PPC, run the 5 Whys on the main cause.
Weekly routine
- Calculate the week's PPC and record the causes of incomplete tasks.
- Update the lookahead: roll forward one week and review constraints.
- Each crew foreman proposes the tasks for next week that he or she is ready to commit to.
- Post the plan on a visual management board on site, with PPC and causes visible.
The meeting should take 30 to 60 minutes and include the crew foremen, not only engineering. The people doing the work must be in the room.
Beyond the Last Planner System
Other practices associated with lean construction: takt planning (fixed rhythm per zone of the building), line-of-balance scheduling, prefabrication, site logistics and visual management. The logic of rhythm and sequence is the same as heijunka in a factory.
Common mistakes
- Using PPC as a stick. If the number becomes punishment, crews promise less or hide failures. Use it to find causes.
- Not recording causes. PPC without causes only shows that the plan fails, not why.
- Planning without the crews. A commitment imposed by engineering is not a commitment.
- Cosmetic lookahead. If constraints have no owner and date, the weekly plan keeps failing.
- Counting partial tasks. 90% done is not done; the next trade cannot start.
- Chasing 100%. A perfect PPC suggests an overly conservative plan. On many projects, values above 80% already indicate a stable flow.
Frequently asked questions
What is lean construction?
It is the application of lean thinking to construction, focused on work flow, waste reduction and client value.
What is the Last Planner System?
A production planning and control system with four horizons, in which the people who do the work commit to tasks that are free of constraints.
How do you calculate PPC?
Fully completed tasks ÷ planned tasks × 100. In the example, 66 ÷ 80 = 82.5%.
What is a lookahead plan?
A medium-term plan, usually 6 weeks, used to identify and remove constraints before a task enters the weekly plan.
What is pull planning?
Planning backward from a milestone, done with the trades involved, defining what each one needs to receive from the one before.
Does lean construction work on small projects?
Yes. On small jobs, a board, a short lookahead and a weekly PPC measurement are enough.
Sources
- KOSKELA, L. Application of the New Production Philosophy to Construction. Stanford University, CIFE Technical Report 72, 1992.
- BALLARD, G. The Last Planner System of Production Control. PhD thesis, University of Birmingham, 2000.
- WOMACK, J.; JONES, D. Lean Thinking. Free Press.
- LIKER, J. The Toyota Way. McGraw-Hill.
Keep studying: trusted sources and links
- Lean Enterprise Institute: What is Lean?
- Toyota Motor Corporation: Toyota Production System
- Wikipedia: Lean manufacturing
Save this address: Manufatura Enxuta is your school for lean manufacturing. Come back whenever you need to study, with a complete article, a visual map and trusted sources. Follow one of the learning paths or check the A–Z glossary.
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About the author
Lean Manufacturing & Behavioral Management Specialist
Over 20 years in the automotive and metalworking industries (GM and Dana), Lean Manufacturing practitioner since 2006. SENAI instructor and mentor in Brazil’s Brasil Mais Produtivo program, delivering consulting, training and audits for 50+ companies, combining quality, productivity and people development.
