Second Stage Theater, the Off Broadway nonprofit producing company, has finalized the purchase of Broadway’s Helen Hayes Theater, ending a legal standoff over the purchase timeline and upping the nonprofit theater presence on Broadway from five theaters (of 40) to six.

Second Stage, the 36-year-old company that has launched commercial successes including “The 25th Annual Putnam County Spelling Bee” and “Next to Normal,” paid a reported $25 million for the venue, which at less than 600 seats is Broadway’s smallest house.

The Rockwell Group, the architecture firm run by set designer David Rockwell, will begin renovations on the theater next year, and Second Stage aims to produce its first show in the venue during the 2017-18 season.

Second Stage will dedicate the theater to showcasing the works of living American playwrights — a demographic that can often feel underrepresented on a Broadway landscape in which star-driven play revivals and British imports can hog all the attention.

Second Stage has intended to purchase the Helen Hayes Theater, one of Broadway’s only independently owned theaters, from Martin Markinson and Jeffrey Tick since 2008. But delay in coughing up the agreed purchase price led to court action earlier this year.

The resolution of that dispute, and the finalization of the purchase, adds one more nonprofit outpost to Broadway, where commercial producers sometimes chafe at the awards attention lavished on nonprofit shows, the financial risks of which are mitigated in part by a producing organization’s not-for-profit status. The Roundabout Theater Company owns three Broadway houses, while Manhattan Theater Club and Lincoln Center Theater have one apiece.

Second Stage is run by founder and artistic director Carole Rothman and executive director Casey Reitz.