The mechanism
A structural steel escalation clause indexes the portion of the contract price tied to structural steel to a published series instead of fixing it at signing. The benchmark is the BLS producer price index for Hot Rolled Steel Bars, Plates, and Structural Shapes, series WPU101704.
Structural steel is a real input cost in structural fabrication, commercial building frames, and bridge and infrastructure work. Its price can move more over a contract term than a fixed-price contingency is built to absorb, so indexing the portion of the contract price tied to structural steel moves that risk onto the published index instead of onto one party.
What's specific to structural steel
This is the mill product a steel fabricator buys, before any cutting, drilling, or welding. A clause on a fabricated structural package often keys to this series rather than the fabricated-metal PPI, because the fabricator passes mill moves through with a lag while charging separately for shop labor.
The calculation, step by step
- Base index value. The index value at the base period, usually the month of contract signing or bid submission.
- Current index value. The index value at the adjustment date, usually the month of delivery or invoicing.
- Ratio. Current value divided by base value.
- Adjustment. Apply the ratio to the portion of the contract price tied to structural steel, not necessarily the whole contract.
Take a clause with a $600,000 scope tied to structural steel, a base index of 260.0, and a current index of 309.0. The ratio is 1.19, a 19% increase, so $114,000 is added to that scope.
Where clauses go wrong
The most common mistake is not naming a series code. "The structural steel index" is not a series. BLS publishes more than one structural steel-related series, so name the exact code, WPU101704, in the contract text.
Clauses also skip the averaging window. A single month's value swings more than a 3-month rolling average, so the clause should say which one applies. Publication lag gets left out the same way: BLS releases data on a delay and revises early figures, so the clause should say whether the preliminary or final value governs.
The last common gap is no cap or floor. With no cap, an index spike passes through in full, which can make a large adjustment commercially unworkable.
Fabricators and owners fight over which index the erected-steel price follows. The fabricated structural-metal PPI includes shop labor and overhead that the owner may already be paying as a fixed line; indexing the steel portion to this mill series and leaving fabrication fixed keeps the two from being escalated twice.
Related
- Escalation clause analyzer: paste a clause and see the formula, undefined terms, and risk score.
- How escalation clause base periods work
- Price adjustment caps and floors