After standing pat for most of 2013, the producer price index that measures construction inputs increased for the second consecutive month in February. A 74 percent year-over-year surge in natural gas prices, attributed to increased heating costs around the country caused by a harsh winter, drove the index's expansion.

Construction materials prices increased by 0.7 percent in February and are up 0.6 percent over the past year, according to the producer price index released by the Labor Department on March 14.

"February marks the second consecutive month in which construction materials prices expanded briskly," Associated Builders and Contractors chief economist Anirban Basu said in a statement. "Construction materials prices experienced a remarkable lack of volatility during the last three quarters of 2013; however, that trend appears to be firmly behind us."

Nonresidential construction materials prices increased 0.7 percent from January to February, and are 0.4 percent higher year-over-year. Crude energy materials prices and natural gas prices led the way, expanding 14.7 percent and 31.5 percent respectively in February. February marked the crude energy segment's largest monthly growth since January 2004.

"The harsh winter is to blame for the spike in energy segment prices," said Basu. "In fact, crude petroleum and natural gas both experienced historic price growth in February. We are certain that February's data reflects the colder-than-normal winter; however, it is difficult to say if increased demand had any part in the month's price growth. With the frigid weather continuing through early March, it may be awhile before we know this winter's true impact.

Natural gas prices are 74 percent higher than February 2013, and crude energy costs increased by 18.1 percent over the prior year. Other increases include prices for crude petroleum, which increased 10.6 percent in February and 3.4 percent year-over-year; prices for concrete products grew 0.9 percent in February and 3.7 percent year-over-year; prices for steel mill products increased 0.7 percent in February and 1.9 percent year-over-year; finally, softwood lumber prices added 0.5 percent in February and are 1.2 percent higher year-over-year.

"Another factor has been a tidal wave of economic news from China, much of which suggests that China's economy is slowing faster than expected," said Basu. "That could cause prices to dip during future months. In any case, greater price volatility should be anticipated."

Only two key construction inputs did not experience price increases in February: nonferrous wire and cable prices fell 0.4 percent on a monthly basis and are down 4.3 percent from one year ago, and iron and steel prices fell 0.4 percent in February but are up 4.3 percent from one year ago.