Units of measure for structural steel
Each piece of structural steel work has its own unit, and keeping them apart is what makes the estimate checkable. These are the units estimators use and how each is measured.
| Item | Unit | How it's measured |
|---|---|---|
| Beams, columns, bracing | tons | Length × weight per foot from the section (a W12x26 weighs 26 lb/ft), summed and ÷ 2,000. |
| Connections and plates | tons or % | Detailed where shown; otherwise an allowance on member weight. |
| Joists and joist girders | each or tons | By designation from the framing plans. |
| Metal deck | SF | Deck area by type and gauge, plus closures and edge form. |
| Pieces | each | Piece count drives erection time as much as weight. |
| Crane | days | From tonnage and pieces per day for the building's layout. |
How estimators take off structural steel
- Take off members by size and length. List every beam, column and brace with its section and length from the framing plans.
- Convert to weight. Multiply length by the section's weight per foot and total by member type.
- Add connections and miscellaneous steel. Detail connections where shown or apply an allowance; take off lintels, embeds and misc. steel separately.
- Take off joists and deck. Joists by designation and deck by area and type.
- Price fabrication and erection. Fabrication per ton from shop quotes, erection from tons or pieces per crew-day plus crane days.
Waste factors and order quantities
Waste covers cut-offs, breakage, laps and spillage, and it's added to the net quantity before rounding up to what the supplier sells. These are typical planning figures; your own job history is the better number.
| Item | Factor | Notes |
|---|---|---|
| Connections allowance | 5 to 15% | Typical planning figure added to member weight when connections aren't detailed. |
| Metal deck | 5% | Typical planning figure for laps and cuts. |
Crew production rates
Labor is quantity divided by production. These rates are per 8-hour crew-day for commercial work, from the same library as the crew-day production estimator: typical mid-range planning values with a low-to-high range, not a promise of output. Crew skill, layout, access and weather move them, and your own crews' records beat any library.
| Activity | Crew | Low | Typical | High | Labor |
|---|---|---|---|---|---|
| Erect structural steel frame | 5 ironworkers, 1 operator | 7 | 10 ton | 14 | 4.80 hrs per ton |
| Install metal floor or roof deck | 4 ironworkers | 2,500 | 3,500 SF | 5,000 | 0.9 hrs per 100 SF |
- Erect structural steel frame 7 to 14 ton, typical 10
- Install metal floor or roof deck 2,500 to 5,000 SF, typical 3,500
Worked example: 250 tons of structural steel
The activity is erect structural steel frame, with a crew of 5 ironworkers, 1 operator at the typical rate of 10 ton per crew-day:
- Crew-days: 250 ton ÷ 10 = 25 crew-days.
- Labor hours: 25 crew-days × 6 workers × 8 hours = 1,200 hours.
- Range: 17.9 crew-days at the high rate to 35.7 at the low rate, a spread of 17.9 crew-days on the same quantity.
- Equipment: Mobile crane, about 25 equipment-days.
Multiply the labor hours by your burdened hourly cost to price the labor. The spread between the low and high rate is why production is the assumption to check first on a structural steel bid: the same takeoff can carry very different labor. Run your own quantities in the crew-day production estimator, and get the burdened rate from the labor burden calculator.
What drives the cost
- Piece count. Many light members take longer to erect per ton than a few heavy ones.
- Crane access. Crane size, setup and mats depend on the site and reach.
- Connections. Moment connections and field welding cost much more than bolted shear connections.
- Coatings. Galvanizing, primers and fireproofing coordination change fabrication cost.
Common exclusions and clarifications
A structural steel price is only as good as the scope it describes. These exclusions come from our scope library for structural and miscellaneous steel (CSI 05 12 00 / 05 50 00); list the ones that apply so the GC levels your number fairly.
- Anchor bolt setting and grouting of base plates.
- Field touch-up painting and finish painting.
- Fireproofing.
- Shear studs, deck openings and reinforcing for openings not shown.
- Crane mats and ground improvement for crane access.
Clarifications that often go with them:
- Anchor bolts furnished by us and set by others.
- Erection sequence per the approved erection plan; one mobilization.
Pick, edit and export these in the scope inclusions and exclusions library, or load them straight into a proposal with the bid proposal builder.
Free tools for structural steel estimating
- Crew-day production estimator: turn structural steel quantities into crew-days, duration and labor hours with the rates on this page.
- Labor burden calculator: find the true cost of a crew hour, with taxes, insurance and benefits.
- Scope inclusions and exclusions library: pick proposal-ready structural steel exclusions and clarifications.
- Bid proposal builder: send a branded structural steel proposal with the scope language loaded.
- Equipment own vs rent calculator: compare the hourly cost of owning a machine with renting it.
- Bond cost estimator: price payment and performance bond premiums on bonded work.