With a positive showing in September, the Architecture Billings Index (ABI) has now seen growth in six of the last nine months, according to the American Institute of Architects (AIA).

The ABI, which reflects the approximate nine- to 12-month lead time between architecture billings and construction spending, rebounded in September with a mark of 53.7. That followed a down month in August, when the ABI sat at 49.1.

September’s score reflects an increase in design services, as any score above 50 indicates an increase in billings. The new projects inquiry index was 61.0, down from a reading of 61.8 the previous month.

“Aside from uneven demand for design services in the Northeast, all regions and project sectors are in good shape,” says AIA chief economist Dr. Kermit Baker. “Areas of concern are shifting to supply issues for the industry, including volatility in building materials costs, a lack of a deep enough talent pool to keep up with demand, as well as a lack of contractors to execute design work.”

The South led all regions with an average of 54.5, followed by the Midwest (54.2), West (51.7) and Northeast (43.7). Sector-wise, mixed practice led the way at 52.6, followed by institutional (51.5), commercial/industrial (50.9) and multi-family residential (49.5).