The U.K. company's chief executive, who had opposed the deal, quit.
The transaction values BPB, the No. 1 producer of plasterboard for building, at 775 pence a share, 7.6 percent higher than the French company's initial offer on Aug. 31. Chief Executive Richard Cousins had spurned four earlier approaches.
``It will be a good deal,'' said David Taylor, an analyst at Teather & Greenwood in London. ``Plasterboard is such a fast-track, labor-saving means of construction that demand is going to carry on accelerating.''
Saint-Gobain, Europe's biggest distributor of building materials, gains leadership in a plasterboard industry with sales growth twice that of construction as a whole. BPB said Nov. 3 its earnings will increase at least 10 percent annually over the next five years as U.S. demand accelerates, U.K. home sales revive and China adopts modern building techniques.
Shares of BPB, based in Slough, southeast England, had gained 57 percent this year prior to today, increasing the company's market value to 3.73 billion pounds. They'd advanced 3.8 percent as of 1:24 p.m. in London, trading below the offer price at 769 pence.