International Paper Co. (IP), the world's largest forest products company, Monday said second-quarter earnings more than doubled on improved building materials prices, lower interest expense, and higher sales volumes in nearly all of its products.

The Stamford, Conn., company reported earnings of $193 million, or 40 cents a share, compared with $88 million, or 19 cents a share, a year earlier.

Excluding special items, the company earned 41 cents a share from continuing operations. On that basis, analysts' average estimate was 38 cents a share, according to Reuters Estimates.

Sales in the quarter rose to $6.5 billion from $6.1 billion a year earlier. Interest expense fell about 6 percent to $183 million.

Earnings at the company's forest products segment, which sells building materials and timberlands, rose more than 90 percent as prices for structural panels and lumber soared.

Many forest products companies, including International Paper, Weyerhaeuser Co. (WY) and Louisiana-Pacific Corp. (LPX), have seen their earnings boosted by high building products prices for four straight quarters. Average market prices for oriented strand board (search), a type of structural panel, nearly doubled and lumber prices (search) jumped about 75 percent from last year.

International Paper said profits at its paper and packaging segments fell from a year earlier, but both businesses showed improvement from the first quarter on higher prices for uncoated free sheet (search), market pulp, containerboard and boxes. Volumes improved at both units.

The company said strong demand should help its paper and packaging units in the third quarter, offset somewhat by lower wood products earnings as well as high transportation, chemical and energy costs.