Architecture Billings Index Declined to 43.3 in September

Washington, DC, October 22, 2025-Business conditions at architecture firms weakened further in September, with the AIA/Deltek Architecture Billings Index (ABI) dropping to 43.3 from 47.2 in August and the lowest since April.  

New project inquiries remained flat while design contract values declined for the 19th consecutive month.

In September, billings declined across all U.S. regions except the Midwest, where they remained flat. Firms in the West experienced the sharpest decline for the fourth consecutive month. By specialization, institutional firms reported the weakest conditions, while commercial/industrial firms saw continued softening after nearing growth over the summer.

“Unfortunately, business conditions remain relatively weak at architecture firms,” said Kermit Baker, PhD, AIA chief economist. “There was some erosion in project backlogs this past quarter, with the greatest slippage coming from firms with an institutional specialization.”

Regional averages were as follows: Midwest (49.8); South (47.9); Northeast (43.8); West (40.6).
The Sector index breakdown was multifamily residential (47.2); commercial/industrial (46.6); institutional (44.3); mixed practice (firms that do not have at least half of their billings in any one other category) (44.0). 

The project inquiries index was 50.1, and the design contracts index was 46.3.