You bid the job off the 60% set. You were careful. You counted every beam, every column, every connection. Your number was tight and it was right.
Then the 80% set shows up. Then the 100% set. Then two addendums.
Somewhere in those revisions, a W12 became a W18. A bay got added on the east end. Moment connections showed up where there were shear tabs. And nobody called you to tell you about it.
I've been in steel erection since 1982, when I started as an apprentice ironworker. I ran a family erection company for years before I sold it in 2012. I can tell you that more erectors lose money on revisions than on bad math. The math is usually fine. It's the drawings that moved.
Why drawing revisions are so dangerous for erectors
Here's how it usually goes. A design team issues drawings in stages:
- 60% set. The building is mostly laid out. Member sizes are preliminary. This is often when the GC asks for budget numbers.
- 80% set. Sizes firm up. Connections get detailed. Things get added that nobody mentioned.
- 100% set. This is supposed to be the final bid set. It's usually followed by addendums anyway.
Every one of those sets can change your tonnage, your piece count, your crane picks and your man-hours. And the changes are rarely called out clearly. Sometimes there's a cloud on the sheet. Often there isn't.
If your price is built on the 60% set and you sign a contract on the 100% set, you just agreed to erect a building you never priced.
The three revisions that cost erectors the most
1. Heavier members. A beam that goes up in size can push a pick past what your crane handles at that radius. Now you need a bigger crane, or a second setup, and your schedule just changed.
2. Added pieces. More beams, more columns, more bracing. Each piece is a pick, a connection and time in the air. Fifty extra pieces on a job is real money.
3. Connection changes. Shear tabs becoming moment connections is a big one. Field welds, bolting and inspection all go up. If your crew size and duration were set for simple connections, you're underwater.
None of these are hard to price. They're hard to find.
How to catch revisions before they catch you
Ask which set you're bidding. Before you open the plans, find out if this is 60%, 80% or 100%. If it's not final, say so on your proposal and price it as a budget.
Put the drawing date and revision on your proposal. List the sheets and dates your number is based on. That one line has saved erectors a lot of arguments.
Compare every new set against the last one. Not a flip-through. A real comparison: sheet by sheet, grid line by grid line. Look for member size changes, added or deleted pieces, and connection changes.
Recount what changed, not the whole job. If you know exactly what moved, you can reprice in minutes instead of starting over.
Ask the GC the hard question. "If the drawings change after we sign, how do we handle it?" Get the answer in writing before you're on the job.
The problem: comparing drawing sets by hand takes forever
On a big job, comparing a 60% set to a 100% set by hand can take a full day or more. Most estimators don't have that day. So they skim it, or skip it, and hope.
That's exactly why we built Document Compare into the AI Takeoff Wizard. You load the 60%, 80% or 100% drawing sets, and it compares them and lists every change by grid line. Member size changes, added pieces, deleted pieces. You see what moved, and you reprice only what moved.
Once you know what changed, the Steel Erection Bid Wizard turns the new counts into an erection price fast. Over 40,000 bid proposals have moved through the Bid Wizard.
Bottom line
You can't control when the architect revises the drawings. You can control whether you catch it.
Know which set you're bidding. Put the revision on your proposal. Compare every new set. And never sign a contract on drawings you didn't price.
If you want to see Document Compare run on a real set of steel drawings, book a free demo. I'll walk you through it myself.
Created by an Erector, For an Erector.