Shares of Virco Mfg. Corp. fell almost 13 percent on Friday after the institutional furniture maker reported a larger quarterly loss and warned of continuing volatility and weaker demand in its core K-12 public school market.

The Torrance company reported a fourth-quarter net loss of $8.9 million (62 cents a share), 13 percent (-7 cents) larger than in the same period a year earlier. Net sales fell 31 percent to $18.1 million. However, the company showed an 8 percent rise in orders during the quarter, enabling it to enter fiscal 2013 with a larger backlog.

Virco cut its full fiscal year loss by 72 percent to $3.8 million, largely by reducing employees from 1,045 to 720. The company also implementing other cost cutting, including a December furlough of plant employees. Virco also benefited from more stable raw material costs.

“As more of our business shifts to furnishing newly constructed schools versus day-to-day replacement of existing classroom furniture, we expect this volatility in shipments and incoming orders to continue, overlaid as always on our strong seasonal pattern of peak summer deliveries and lower fall, winter, and spring shipments,” Chief Executive Robert A. Virtue said in a statement.

Shares closed down 31 cents, or 13 percent, to $2.18 on the Nasdaq.