Freshfields Bruckhaus Deringer has taken the lead opposite a raft of US firms to advise on the $1.8bn (£917m) joint venture between building material producers Owens Corning and Saint-Gobain.

The magic circle firm advised longstanding client Saint-Gobain, which has combined its glass reinforcements business with that of Owens Corning to create OCV Reinforcements.

Paris head Jean-Claude Cotoni led the Freshfields team, which included lawyers from France, Belgium, the US, Asia and Russia. He was assisted by New York corporate partner Timothy Wilkins and Brussels competition partner Frank Montag, who is the Saint-Gobain relationship partner.

Freshfields used domestic law firms in jurisdictions where it had no office, such as Brazil.

Cleary Gottlieb Steen & Hamilton Brussels corporate partner Jacques Reding advised Owens Corning in Europe, while Arnold & Porter advised on the US aspects. Morgan Lewis & Bockius advised Owens Corning outside the US and Europe.

Owens Corning will now hold a 60% stake in OCV Reinforcements, while Saint-Gobain will take the remaining 40%. After four years Owens Corning will have the option to acquire the Saint-Gobain stake.

Montag commented: "The two companies are leaders around the world and so there were a lot of associated regulatory issues, coupled with coordinating corporate teams around the world. There are antitrust notifications in 14 jurisdictions, including in the UK, the European Commission and the Federal Trade Commission."

Freshfields has advised Saint-Gobain for 20 years. Other advisers to the company have included Slaughter and May and Macfarlanes, while Linklaters won its first major instruction for the client in 2005. The company specialises in the design, production and distribution of materials for the construction, industrial and consumer markets.

The deal, which was signed on 20 February and is subject to antitrust approval, is expected to close in the second quarter of 2007.