Permits issued over the past year to build multifamily housing units slid below pre-pandemic levels amid a surge in project costs and flattening rents, Redfin (RDFN) said in a report published Friday.

From April 2024 to March this year, developers secured permits to build 12.4 multifamily units for every 10,000 people in the US, compared with permits for 13.1 units per 10,000 people in the years before the pandemic. The latest figure is 27% lower than the level during the 2020-2023 pandemic boom, according to the real estate brokerage.

Redfin said its analysis was based on Census Bureau data covering permits for buildings with five or more units.

Rental demand surged during the pandemic, when remote work become the norm, though rents are flattening now, Redfin said. The median US asking rent fell 0.6% year over year in March, and rose 0.4% sequentially, it said last month.

"New apartments are being rented out at the slowest speed on record and builders are pumping the brakes because elevated interest rates are making many projects prohibitively expensive," Redfin Senior Economist Sheharyar Bokhari said in a statement on Friday.

The slowdown in building means there will be fewer options for renters next year, which could push rents higher, Bokhari warned.

Among the 78 US metros Redfin analyzed, Austin attracted the biggest number of building permits over the past year, while Stockton in California recorded no new permits.