Boral says it will return up to $3 billion in capital to shareholders as it heads into the final stages of an asset sale program centred on the exit from two large North American businesses.

The company told the ASX on Monday that settlement of the $US2.15 billion ($2.96 billion) sale of its United States building products business to Westlake Chemical occurred on October 1. The sale of the roofing, stone and window businesses was announced in July. Westlake is listed on the New York Stock Exchange and based in Houston.