As expected, housing continues to get hammered in the aftermath of the tax credit expiration.

The National Association of Realtors’ (NAR) pending home sales index plummeted 30% in May, to a reading of 77.6, according to data released Thursday by the NAR. That’s the lowest level of contract-signing activity for existing homes since the association began tracking such data in 2001.

On an annual basis, the index stands 15.9% below May 2009.

“Consumers are rational and they rushed to meet the tax credit eligibility deadline in April,” explained Lawrence Yun, NAR’s chief economist. “The sharp decline in contract signings in May is a natural result with similar low levels of sales activity anticipated in June.”

Yun is correct: Many had expected this particular statistic to fall, given the April 30 deadline for the tax credit, but the drop also exceeded analysts’ expectations.

Still, industry watchers urged patience, reminding investors and others that housing numbers are likely to remain volatile in the months to come, even as the market finds firmer ground. “We continue to believe the housing market remains in a period of stabilization to modest improvement over the next 12 to 18 months, concurrent with a modest economic recovery,” said Michael Rehaut of J.P. Morgan’s North American equity research.

In other housing stat news, total U.S. construction spending slipped 0.2% in May to a seasonally adjusted level of $841.9 billion, according to information released Thursday by the U.S. Census Bureau. This is down 8% from May 2009.

But Patrick Newport, U.S. economist for IHS Global Insight in Lexington, Mass., saw a number of bright spots in the release. “Data revisions, which go back to 2004, show that the downturn in construction was deeper than previously thought,” he said. “But they also offer hints that the worst may be behind us. True, construction spending slipped 0.2% during May. But this followed solid increases in March and April.”

Single-family construction spending improved slightly, by 0.8% to a seasonally adjusted pace of $121.5 billion, likely due to activity generated by the housing tax credit. This represents the category’s “weakest gain in 12 months,” according to Newport, who predicts falling numbers for the coming months given recent drops in housing starts.

On an annual basis, single-family construction spending is up 31.2% compared to May 2009.

Apartments and condos did not fare so well. “Multifamily housing construction spending fell 6.3% in May--dropping to a $13 billion annual rate, the lowest level since April 1994,” Newport said. “The only good thing about these awful numbers is that spending levels are not likely to fall much further because they are almost touching the bottom.”

Year-over-year, multifamily construction spending in June was off 57.1%.

Alison Rice is senior editor, online, at BUILDER magazine.