Construction spending in September climbed to a nearly three-year high at an annualized rate of $852 billion, as increased spending on houses, apartments and private nonresidential projects outweighed a continuing downturn in public construction, according to an analysis of new federal data recently released by the Associated General Contractors of America. Association officials said they expect both the public and private trends to continue despite the disruption caused by Hurricane Sandy.

“It is heartening to see the growth in total spending, but the progress remains fragile and fragmentary,” said Ken Simonson, the association’s chief economist, noting that construction spending had dipped the previous month and that spending in several categories remains lower than in September 2011. “In the wake of the massive losses from this week’s storm, many construction priorities will be reordered, but overall private and public spending patterns are likely to stick unless federal and state lawmakers devote more funds to construction.”

Simonson noted that total construction spending rose 0.6% for the month and 7.8% from September 2011 to September 2012, bringing the total to the highest level since October 2009. Private residential spending accelerated, increasing by 2.8% compared with August and 21% during the past 12 months. Private nonresidential construction, however, inched down 0.1% for the month, but remains up 8.8% for the year. Public construction shrank 0.8% in September and 4.2% year-over-year.

Within the private sector, all three residential categories did well. New single-family construction increased 3.9% for the month and 26% over 12 months. New multifamily construction rose 1.3% for the month and 49% since September 2011. Improvements to existing residential structures—a category likely to get a large boost from storm reconstruction—climbed 2.0% in September and 12% over the year.

Among private nonresidential categories, the largest—power construction, which includes oil, gas and other energy projects—rose 1.1% for the month and 20% over 12 months. Manufacturing construction was up 3.8% in September and 1.3% year-over-year.

Commercial construction, comprising retail, warehouse and farm structures, dropped 3.8% in September but posted a 12-month gain of 4.4%.

Public construction fell for the third straight month, with declines in the two dominant categories. Highway and street construction spending decreased 1.6% in September and 2.4% year-over-year, while educational construction spending slipped 0.8% and 6.9%, respectively.