The Three Wastes Eating Your Margin — and How Full Kits Fix Them
- Apr 20
- 6 min read
Issue 4 · April 23, 2026
Walk any active jobsite for twenty minutes with a stopwatch and you can measure a problem most PMs have learned to stop seeing. Count the people waiting. Count the materials sitting in boxes they shouldn't still be in. Count the work that's being done a second time because someone got it wrong the first time. Then add up the cost. That's not overhead. That's the job quietly bleeding out.
Taiichi Ohno — the Toyota engineer who built the production system the entire lean movement is descended from — had a word for all of that: muda. Waste. In Toyota Production System: Beyond Large-Scale Production (1988), he argued that almost every improvement effort fails because teams try to speed up the value-adding work instead of hunting down the waste surrounding it. He named seven categories: overproduction, waiting, transportation, over-processing, inventory, motion, and defects. His claim was simple and uncomfortable — in most operations, the share of true value-adding time is surprisingly small. Lauri Koskela carried the idea into construction in his 1992 CIFE report Application of the New Production Philosophy to Construction, and empirical studies since have estimated that non-value-adding activity can account for more than half of total construction time.
FMI Corporation puts a harder number on it. More than $177 billion is lost every year in the U.S. construction industry to rework, communication breakdowns, and time spent hunting for information that should have been at someone's fingertips. That number doesn't live in your bid. Your bid is what's left after somebody — an owner, a GC, a sub — has already absorbed the cost of waste into the price of getting the job done.
You don't need to memorize all seven categories to get value out of Ohno's framework. Pick the three that cost commercial construction the most and learn to see them.
Waiting. This is the big one on any commercial job. A paint crew shows up on schedule but the drywall isn't punched. The tower crane sits idle because the pick plan wasn't finalized. The finish electrician is ready to trim devices but the ceiling grid hasn't closed in. Every one of those minutes gets paid for — either directly through labor hours or indirectly through the schedule slipping and extended general conditions eating your fee. Waiting is also the waste that creates the most downstream waste. People who have nothing to do start improvising, which leads to the next two.
Defects and rework. The handrail crew shows up and finds the in-wall blocking is missing — or an inch off. The handrail doesn't get installed wrong. It just doesn't get installed. The crew leaves. The framer comes back to rework the blocking. The handrail crew gets rescheduled. Every trade that was going to follow through that area shifts a week. That's before you count the direct cost of the rework itself. Studies consistently put total construction rework at 5–12% of project value. On a $40 million project, that's a couple million dollars of margin you're giving back to a system that didn't catch the problem upstream.
Inventory. This one is less obvious. A lot of PMs treat piles of material on site as a sign of progress. Ohno would have called it a liability. Material stored on the jobsite gets double-handled, damaged, stolen, buried, or simply forgotten. It also hides problems. If a trade ordered three weeks of material at once because they weren't sure the schedule would hold, you've learned something — but only if you notice it. In steel specifically, with lead times running six to twelve weeks right now and prices still climbing, the temptation is to overbuy early. That's rational. But it's still inventory, and the cost of holding it — cash tied up, yard space consumed, damage risk — needs to be in the math.
The proactive move: full kits. Counting waste after it happens is a start, but a tally won't save margin that's already gone. The higher-leverage move is to stop the waste from starting. Every crew on your weekly work plan needs the same three things before they touch the work: material, access, and direction. All the material they need, on site and staged in the right zone. Access to the work area — predecessor work complete, inspections cleared, safe to enter. And direction — RFIs answered, drawings current, submittals approved, scope understood. In lean construction, that's called a full kit. The concept comes from Eliyahu Goldratt's Theory of Constraints: don't release work to the system until every prerequisite is ready.
Full kits make the three wastes above stop happening. Crews don't wait, because everything they need is already there. They don't rework, because the direction is right and the conditions are right. They don't stockpile inventory, because you've only brought what the week actually calls for.
So spend your proactive time on kits. Before Monday's weekly work plan meeting, walk every commitment on the plan and verify its kit. If material, access, or direction isn't ready, don't let that task start — park it, and pull something else forward that does have a full kit ready. That's harder than it sounds. It means telling a foreman “not this week” on a task they were counting on. But it's where the margin actually gets protected, and it's what being proactive looks like in practice.
Something to consider Even with full kits, some waste still leaks through — a missing tool, a last-minute change, a truck that came in late. Those patterns only show up if you capture them over time, and most PMs don't have time to write while they're walking. That's where voice-to-text changes the math. Walk the job with your phone in your pocket and narrate what you see. “Two plumbers waiting on the framer at grid D-7.” “Rework on the west stair — blocking missing.” “Three pallets of ACT tile in zone 2 not needed until next month.” Thirty seconds per observation. At the end of the walk, you have a transcript. Paste it into an AI tool and ask it to categorize each observation by waste type and location. What you get back isn't a magic answer — it's a clean log. After a month of walks, the patterns show up: which trades generate waiting most often, which kit elements keep breaking, which areas accumulate inventory. That feedback loop is what makes next week's kits better.
Steel Market Snapshot
Mid-April 2026
Mills gain ground as utilization climbs. Nucor raised its hot-rolled spot price again on April 13, and AISI reported the highest capacity utilization rate since September 2024. Upward pressure on pricing is holding steady even as demand remains mixed.
HOT-ROLLED COIL $1,045 /ton ▲ Up $5/ton from prior week | PLATE $1,160–1,210 /ton ▲ Lead times ~7+ wks |
BEAMS +$120 /ton YTD ▲ Lead times 10–12 wks | REBAR $960–980 /ton ▲ Post-$60 March hike |
Hot-rolled coil is at $1,045/ton after Nucor's April 13 $5 increase — its eighth consecutive weekly or monthly move higher. Lead times are around 6.5 weeks. The company also announced a $10/ton minimum fuel surcharge effective May 1.
Plate is trading in a range of $1,160–1,210/ton, averaging about $1,185/ton on spot. Lead times have stabilized at just over 7 weeks — multi-year highs — and market participants are flagging potential shortages of certain domestically produced plate grades as Section 232 changes take full effect.
Beams continue to run roughly $120/ton above early-2026 levels. Lead times remain 10–12 weeks. Import competition has softened under the tariff expansion but hasn't disappeared.
Rebar is holding near $960–980/ton (short ton basis) after the March $60 hike from Nucor and Gerdau worked through the market. West Coast mill lead times are 4–6 weeks.
What to watch: Mill capacity utilization hit 79.8% the week ending April 11 — the highest in over a year and approaching the 80% threshold mills typically defend with further price moves. Nucor's May fuel surcharge is worth pricing into any Q3 buyouts. For precon teams, the pattern is now six months deep: lock pricing where the schedule allows, and assume lead times hold rather than soften. For live data, visit our Market Informer page.
Sources & Further Reading
1. Ohno, Taiichi. Toyota Production System: Beyond Large-Scale Production. Productivity Press, 1988. routledge.com
2. Koskela, Lauri. Application of the New Production Philosophy to Construction. CIFE Technical Report #72, Stanford University, 1992. stanford.edu
3. Koskela, Lauri. “Making-Do — The Eighth Category of Waste.” Proceedings of the 12th Annual Conference of the International Group for Lean Construction, 2004. iglc.net
4. Goldratt, Eliyahu M. Critical Chain. North River Press, 1997. amazon.com
5. FMI Corporation. “How Poor Design Drives $177B in Construction Rework.” Trimble Blog, 2018. trimble.com
6. Lean Construction Blog. “Understanding the 7… No, 8… No, 10 Forms of Wastes.” leanconstructionblog.com
7. Steel Market Update. “Nucor Raises HR Spot Price to $1,045/ton.” April 13, 2026. steelmarketupdate.com
8. Steel Market Update. “SMU Survey: Sheet and Plate Lead Times Stabilize at Multi-Year Highs.” April 2, 2026. steelmarketupdate.com
9. Steel Market Update. “Plate Sources Say Uncertain Market Conditions Persist.” April 17, 2026. steelmarketupdate.com
10. Steel Market Update. “AISI: Raw Steel Production Rises to Four-Year High.” April 13, 2026. steelmarketupdate.com
11. GMK Center. “Nucor Raises Rebar Prices by $60/t.” March 2026. gmk.center
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