The Architecture Billings Index (ABI) slipped in August after showing mostly healthy business conditions so far this year.

As a leading economic indicator of construction activity, the ABI reflects the approximate nine- to 12-month lead time between architecture billings and construction spending.

The American Institute of Architects reported the August ABI score was 49.1, down from a mark of 54.7 in July. This score reflects a slight decrease in design services (any score above 50 indicates an increase in billings).

The new projects inquiry index was 61.8, down from a reading of 63.7 the previous month.

“Over the past several years, a period of sustained growth in billings has been followed by a temporary step backwards,” said AIA Chief Economist Kermit Baker. “The fact that project inquiries and new design contracts continue to grow at a healthy pace suggests that this should not be a cause for concern throughout the design and construction industry.”

Key August ABI highlights:

• Regional averages: Midwest (56.1), South (53.8), West (50.2), Northeast (46.8).

• Sector index breakdown: institutional (53.7), mixed practice (52.8), commercial / industrial (49.7) multifamily (49.5).

• Project inquiries index: 61.8.

• Design contracts index: 55.3.