A condo owner on the Lower East Side transformed a single apartment into 11 illegal, windowless micro-apartments – some so tiny their ceilings were only four-and-a-half foot high, according to a report.

The New York Post reported the conversion at 165 Henry St. between Jefferson and Rutgers streets, which forced the Department of Buildings to vacate the site last week.

The 11 windowless units were set up inside of a 634-square-foot condo on the fourth floor where nine people were living, Buildings Department inspectors told the Post. A second floor had been built within the condo to cram in the tiny units.

“Tenants living in truncated and windowless dwelling units like this poses an extreme hazard to their safety, as well as the safety of their neighbors and first responders — a hazard that cannot be tolerated in our city,” DOB spokesperson Andrew Rudansky told the Post.

After the Post reported on the tight quarters, another apartment at 165 Henry St. was found to also be subdivided into windowless units — with ceilings four feet high and staircases built without permits, according to the newspaper.