Steel erection costs: price the crane by picks, not tons

Erection estimating · ~7 min read

The most common erection estimating mistake is treating the crane like labor: divide the field hours by the crew and call that the schedule. The crane doesn't work that way. Its day is spent in a cycle whose length barely cares what's on the hook.

Why tonnage is the wrong driver

Watch a raising gang for an hour and count what actually takes time: hook on, lift, swing, land, hang two bolts per end (the OSHA minimum before release), unhook, swing back. Almost none of that cycle changes whether the piece is a W12X26 or a W21X62. A heavy job and a light job with the same piece count erect in roughly the same number of crane days; the heavy job just moves more tons in them.

That's why published erection rates are quoted in pieces. Working figures from public sources cluster tightly:

A planning number in the mid-20s per crane per day is a sound starting point for conventional low-rise work. Complex rigging, tight sites, and field-welded connections pull it down; a repetitive one-story frame with truck access under the hook pulls it up.

The crew doesn't shorten the crane

Here's the part that breaks the labor-style math. The crew working a crane is a raising gang of about five: a foreman, two hooking on at the ground, two connecting up top. That gang is sized to the crane's cycle. Add two more ironworkers and the crane does not go faster; the extra hands stand around, or you've actually started a second gang, and a second gang needs a second crane.

So keep two separate calculations:

• Labor duration scales with crew: field hours ÷ (crew size × hours per day). This prices the ironworkers.
• Crane duration scales with picks: piece count ÷ picks per day. This prices the equipment, and it's crew-independent.

On most jobs the two land close together, because the gang is sized to the crane. When they don't, believe the picks: a 300-piece frame at 25 picks a day is 12 crane days no matter what the labor math says, and quoting 8 days of crane on it is a hole in the bid.

Building the erection number

1. Count the picks from the takeoff

   Every shipped piece that flies is a pick: beams, columns, braces, and the misc that goes up on the hook. A takeoff kept by piece gives you this for free; a takeoff kept only in tons doesn't, which is one more reason to keep it by piece.

2. Pick a picks-per-day rate for the site

   Start in the low-to-mid 20s per crane. Adjust for height, access, connection type, and how repetitive the frame is. Your own last few jobs beat any published figure.

3. Size and price the crane for the duration

   Piece count ÷ rate = crane days. Then price the machine that the heaviest, farthest pick requires, not the average one. A 100-ton crawler runs roughly $3,000 – $5,000 per day; carry mobilization in and out as its own line.

4. Price the labor separately

   Field hours ÷ (gang × hours) gives the labor duration, at your field rates. Keep it a separate line from the crane so a change in one doesn't silently reprice the other.

5. Sanity-check against $/ton bands

   Once the bottom-up number exists, divide by tonnage and compare against typical erection $/ton ranges. Outliers usually mean a missed mobilization, a wrong rate, or a pick count that included loose material.

Common holes in erection bids

• Equipment buried in a labor rate. When the crane hides inside an hourly composite, nobody notices it's wrong until the job is running.
• One crane priced, two needed. If the schedule requires two gangs, it requires two machines. Check the calendar, not just the hours.
• Small picks ignored. Stairs, rails hung with the hook, and roof frames are picks too. They're light, and they cost the same cycle as a beam.
• Weather and site days. Crane days are calendar days; a rate that assumes zero lost days is an optimistic rate.

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