Contractor Backlog Rose to 8.7 Months. Data Center Firms Hold 11.3.

Construction backlog rose for a second straight month in September, and the trade group that tracks it credited data center work for the gain. Associated Builders and Contractors put its Construction Backlog Indicator at 8.7 months, up 0.2 months from August and 0.2 months from September 2025, in a reading released October 13. The figure represents how many months of contracted work the average member firm has in hand.

The data center effect shows up in the breakdown. Fifteen percent of ABC member firms reported being under contract for data center work, and those firms averaged 11.3 months of backlog, about three months more than members without it. The work is concentrated by company size: 39 percent of contractors with more than $100 million in annual revenue hold data center contracts, compared with roughly one in ten firms below that threshold. The survey ran September 21 through October 5.

The rest of the reading was mixed. Commercial and institutional backlog climbed to its highest level since July 2025 after sagging in mid-2026, while heavy industrial backlog dropped to its lowest point since March, even though it remains half a month above where it stood a year ago. On ABC's companion Construction Confidence Index, staffing expectations rose while sales and profit margin expectations fell. Sales expectations hit an 11-month low, and more than one in four contractors expect margins to shrink over the next six months, the largest share since November 2025. All three components stayed above 50, the line separating expected growth from contraction.

Backlog measured in months is the number contractors use to decide whether to carry crews between jobs. A pipeline near a year long justifies keeping journeymen and apprentices on payroll through a gap, running a second shift, and committing to prefabrication and tooling. An eight-month pipeline does not. That is why the confidence split matters: staffing expectations improving while margin expectations weaken means hiring is being driven by work already under contract rather than by pricing power. ABC Chief Economist Anirban Basu said backlog rose "as data center work continues to keep contractors busy."

The hiring consequence is a question of which employers hold the long book. Large firms have most of the data center contracts, so that is where the multi-year assignments, travel packages, and continuous apprentice intake sit. The pressure is already measurable. ENR reported in September that an AGC and NCCER survey found 28 percent of contractors had performed data center work in the prior year, and among firms reporting workforce effects, 58 percent cited more competition for skilled workers and 49 percent cited higher wage pressure. Federal payroll data points the same direction. Nonresidential specialty trade contractors, the category that includes commercial electrical contractors, added 12,000 jobs in September, while construction employment overall changed little at 11,000 against a 12-month average of 10,000.

Backlog is a forward-looking measure, not a record of work performed. September's reading says the data center pipeline is still filling, and that it is filling unevenly.