The Last Planner System: Why Your Weekly Plan Falls Apart — and How to Fix It
- 2 hours ago
- 5 min read
Issue 3 · April 9, 2026
Your weekly plan says the drywall crew starts Tuesday. The electricians are supposed to rough in by Thursday. The plumber promised to finish overhead before anyone else moves in. By Friday, none of it happened the way it was drawn up. Not because people didn't try — but because no one stopped to ask whether those commitments were actually reliable before they went on the schedule.
This is the problem Glenn Ballard and Greg Howell set out to solve when they developed the Last Planner System at the Lean Construction Institute in the late 1990s. Their research found something that should bother every PM in the industry: on average, only about 54% of weekly planned tasks actually get completed on time. That means nearly half the work your team committed to this week won't get done this week. And the ripple effects — crews standing around, materials stored in the wrong place, trades stacking up in zones that aren't ready — are where your margin goes to die.
The Last Planner System doesn't start with software or a new meeting format. It starts with a different question. Instead of building a schedule from the top down and handing it to the field, you ask the people who actually do the work — the foremen, the crew leads, the trade partners — what they can commit to. Not what the master schedule says they should do. What they will stake their name on finishing.
Jason Schroeder, who teaches lean construction through Elevate Construction, puts it plainly: the Last Planner System is built on the idea that a promise is only as good as the person making it — and that person needs to have the authority, the information, and the resources to keep it. Schroeder's framework breaks planning into layers. The master schedule sets the milestones. Phase planning (pull planning) works backward from those milestones with the trades in the room. The lookahead — usually six weeks out — identifies constraints: what needs to be true before each task can start? And the weekly work plan is where the rubber meets the road. Every Monday, last planners meet and make specific, measurable promises about what their crews will complete that week.
The metric that holds it all together is Percent Plan Complete — PPC. At the end of each week, you count: how many of our promises did we actually keep? Not how many tasks moved forward. Not how much progress was made. How many commitments were fulfilled exactly as promised. Ballard and Howell's research showed that projects consistently hitting 80% PPC or above were far more likely to finish on time and on budget. Schroeder pushes teams to target 100%, and with Takt-based plans, he argues that's realistic — not sandbagging.
But here's the part most teams miss: PPC isn't a scorecard for punishment. It's a learning tool. When a promise breaks, you ask why. Was the constraint not removed? Was the predecessor work incomplete? Did the crew overcommit because they didn't want to say no in the room? Those root causes — tracked over weeks — are where the real improvement lives. The pattern shows you whether your system is failing people or whether individual promises need to be sharper.
The practical move for this week: at your next Monday planning meeting, try asking each trade partner to make exactly three promises for the week. Not a list of fifteen tasks. Three specific commitments they are confident they can keep. Write them on a whiteboard where everyone can see them. On Friday, check: did each promise get kept? If not, why? Do that for four weeks straight and you'll have a dataset that tells you more about your project's health than any Gantt chart ever will.
Something to consider The weekly work plan is only as reliable as the constraint identification that feeds it. Try taking your six-week lookahead and pasting it into an AI tool. Ask it to flag every activity that has an unresolved predecessor, a pending submittal, or a missing RFI response. Then bring that list to your Monday meeting. It doesn't replace the conversation — the foremen still need to make their own commitments — but it gives you a cleaner starting point. Instead of spending the first thirty minutes figuring out what's ready, you walk in already knowing what's blocked. That's thirty minutes you can spend on the promises themselves.
Steel Market Snapshot
Early April 2026
Tariff shift adds new uncertainty. New Section 232 modifications took effect April 6, expanding full-value tariffs to cover derivative steel imports including pipe and tube. The 50% tariff rate remains in place. Mills continue to hold pricing power as supply stays tight.
HOT-ROLLED COIL $1,035–1,050 /ton ▲ Up ~$205/ton since Sep '25 | PLATE $1,130–1,180 /ton ▲ Lead times 6–9 wks |
BEAMS +$120 /ton YTD ▲ Lead times 10–12 wks | REBAR $1,040 /ton ▲ Up $60/ton since Nov '25 |
Hot-rolled coil is trading near $1,035–1,050/ton, up from $830/ton in September 2025. Nucor pushed another $10/ton increase in late March — the sixth consecutive monthly rise, driven more by supply discipline than demand strength.
Plate is at $1,130–1,180/ton, with lead times of 6–9 weeks and tightening further. Market participants are flagging potential shortages in certain domestically produced plate grades as the tariff expansion takes hold.
Beams are holding at roughly $120/ton above early-2026 levels. Lead times remain 10–12 weeks. Import beams are still competitive despite the 50% Section 232 tariff.
Rebar sits around $1,040/ton (short ton basis), up $60/ton since November. Lead times are 4–6 weeks from West Coast mills.
What to watch: Today's tariff expansion to derivative products could tighten supply further in downstream segments. Mill capacity utilization is at 77.2% — still below the 80% target, suggesting mills are managing output deliberately. Over four million tons of new steelmaking capacity is expected online in the next two years. For precon teams, the message is the same as last month: lock pricing early where you can. For live data, visit our Market Informer page.
Sources & Further Reading
1. Ballard, Glenn and Howell, Greg. "The Last Planner System of Production Control." Lean Construction Institute, 2000. leanconstruction.org
2. Schroeder, Jason. Ten Improvements to Lean Production Planning. Elevate Construction IST, 2024. amazon.com
3. Schroeder, Jason. "The Last Planner System — Lean Series." Elevate Constructionist. elevateconstructionist.com
4. Steel Market Update. "SMU Price Ranges: Sheet and Plate Prices Flat or Up." March 31, 2026. steelmarketupdate.com
5. Steel Market Update. "Sheet and Plate Lead Times Stabilize at Multi-Year Highs." April 2, 2026. steelmarketupdate.com
6. GEODIS. "United States Announces Changes to Section 232 Steel, Aluminum, and Copper Tariffs Effective April 6, 2026." geodis.com
7. GMK Center. "Nucor Has Again Raised the Price of Hot-Rolled Coil by $10 Per Ton." March 2026. gmk.center
8. AISI. "AISI Applauds Action to Maintain Section 232 Steel Tariffs." April 2026. steel.org
Champion Steel Works — Steel you can trust.