U.S. homebuilding tumbled in April and permits fell, suggesting the housing market continued to tread water amid shortages of land and skilled labor.

Housing starts dropped 3.7 percent to a seasonally adjusted annual rate of 1.287 million units in April, the Commerce Department said on Wednesday. The drop reversed March’s rise.

Data for March was revised to show starts rising to a 1.336 million-unit rate instead of the previously reported 1.319 million-unit pace. Building permits fell 1.8 percent to a rate of 1.352 million units.

Economists polled by Reuters had forecast housing starts falling to a pace of 1.310 million units last month and permits declining to a 1.350 million-unit rate.

Single-family home building, which accounts for the largest share of the housing market, edged up 0.1 percent to a rate of 894,000 units last month. Single-family homebuilding has lost momentum since setting a 948,000-unit pace last November, which was the strongest in more than 10 years.

Residential construction has been hamstrung by rising prices for building materials and shortages of land and skilled workers.

While a survey on Tuesday showed confidence among single-family homebuilders perked up in May, builders complained that “the record-high cost of lumber is hurting builders’ bottom lines and making it more difficult to produce competitively priced houses for newcomers to the market.”

The Trump administration in April last year imposed anti-subsidy duties on imports of Canadian softwood lumber. These constraints have left builders unable to plug an acute shortage of houses on the market, restraining home sales growth.

Permits for the construction of single-family homes rose 0.9 percent to a rate of 859,000 units in April.

Last month’s gain in single-family starts was outpaced by an 11.3 percent decline in groundbreaking activity on multi-family housing units.