Over the last few weeks, developers have been concerned and confused over a decision by the New York City Department of Buildings to enforce a 56-year-old zoning rule banning outdoor terraces.

A provision of the zoning code implemented in 1961 states "all uses must be contained within buildings," shutting down a common practice of building owners turning unused outdoor space into flea markets. The DOB has begun cracking down on the popular usage of outdoor terraces as amenity spaces for multifamily and office buildings alike, the New York Post reports.

Several high-profile developments under construction have terraces planned, and the new DOB policy throws such plans into question and could cause multimillion-dollar delays and plan changes. After widespread outcry from organizations such as the Real Estate Board of New York, the Department of City Planning met with the DOB on Thursday over the enforcement change, according to the Post.

Though a representative of the DCP said discussions were ongoing, a source told the Post the DOB has "dug in their heels."