LANCASTER — Armstrong World Industries Inc. said Monday its fourth-quarter net loss widened due to rising lumber prices, declines in remodeling and new home construction in North America and special items.

The results missed Wall Street expectations, and its shares fell $1.63, or 3.7 percent, to $42.24 in late morning trading.

The Lancaster maker of flooring and building products reported a net loss of $21 million, or 36 cents per share, for the quarter ended Dec. 31, versus a net loss of $3.8 million, or 7 cents per share, a year earlier. Revenue fell 1.5 percent to $643 million from $653 million.

Excluding special items including cost reduction initiatives and asset impairments, the company said it would have had adjusted earnings of $6.3 million, or 11 cents per share.