WASHINGTON — Sales of new single-family houses in February 2014 were at a seasonally adjusted annual rate of 440,000, according to estimates released jointly by the U.S. Census Bureau and the Department of Housing and Urban Development. This is 3.3% below the revised January rate of 455,000 and is 1.1% below February’s level of 445,000. The median sales price of new houses sold in February 2014 was $261,800; the average sales price was $317,500. The seasonally adjusted estimate of new houses for sale at the end of February was 189,000. This represents a supply of 5.2 months at the current sales rate.