KMI Cost Index – September 2026
The September 2026 Cost Index reflects continued upward cost pressure through Q3, with Building Cost increasing 1.00% and Construction Cost increasing 0.70%. Material Cost was the primary driver of escalation, rising 2.20%, while labor remained flat, with both Common Labor and Skilled Labor showing 0.00% monthly change. The largest material increase came from Structural Steel at 7.40%, signaling significant pressure in structural framing and steel-related scopes, followed by Cement at 2.60%, Lumber at 1.70%, and Plywood at 1.00%. Gypsum Board was the only tracked material to decline, decreasing 0.90%, which provided some offset but did not outweigh the broader upward movement in the material basket. Overall, the September report points to a material-driven cost environment and reinforces the need for active procurement tracking, commodity monitoring, and targeted material contingencies.
Click on the link above to view the latest cost data for September 2026.