AMHERST — Appeals for more documentation of a historic performance space in a downtown building, possibly used by an Amherst College fraternity in the 19th century, are being made before the three-story brick structure is razed.

The rear ell at 45 South Pleasant St. is one of two buildings — with the other being a two-story wood-framed building at 55 South Pleasant St. that was the longtime home of Jeffery Amherst Bookshop — that are subject to a six-month demolition delay imposed by the Historical Commission in October.

With the delay set to expire this spring, though, there are questions about allowing developers to move forward on construction of a new mixed-use building, to be attached to the rear of the existing AJ Hastings building, at 45 South Pleasant St., and necessitating the removal of the ell.

At a recent commission meeting, member Hetty Startup described a recent tour of the Fretted Instrument Workshop, which is on the second floor of the Hastings building, but which also uses a portion of the ell, including a second-floor room with a barrel vaulted ceiling. This part of the building Startup calls “a most Dickensian space,” with original gaslight lamps, and where performances may have happened in the 19th century.

Records provided to the commission by Senior Planner Nate Malloy show that around 1857 the Gamma chapter of the Psi Upsilon fraternity moved to a hall in the Sweetser block that “consisted of the third story of the Cutler building, and the use of two stairways, and rented for $200 per annum” and that in 1875 the chapter was using the space “on many occasions for lectures, performances, and perhaps for chapter meetings.”

Whether this is the same space that is in the ell is uncertain, in part because of the Merchants Row July 4, 1879 fire, which started in a shed behind George Cutler’s store. That fire consumed much of the block, though the 55 South Pleasant St. building is believed to have survived, and the ell may have, as well.

Startup points to research done by late Amherst historian Ed Wilfert. Wilfert examined the George Cutler & Co. papers, and, armed with this information, wrote that it suggests “that the present back building was not rebuilt ... which I think was Sweetsers’ Hall.”

A lot of questions need to be answered, even with photos, documentary and oral history evidence already provided, Startup said. “I feel like we’re not in good shape enough to tell the story of what is really going on there,” Startup said.

Malloy said the commission could condition the demolition on requiring certain things from the applicant, such an updated inventory form and photographs. Photographs were taken during the winter of the inside of the ell, including the barrel vaulted ceiling in the Fretted Instrument work space, as well as a former water closet and an exterior staircase.