Thirau was founded in March 1952, under the name Thiro Construction Ltd. Among its first clients were Shawinigan Water & Power and Montreal Light, Heat & Power (which gave birth to the Québec Hydro-Electric Commission – known today as Hydro-Québec).

Between the years of 1980-1990, Thiro’s activities underwent strong growth during the improvement of Hydro-Québec’s electricity transmission and distribution network through the expansion of its territory made possible by its American subsidiary, Thiro U.S.A.

In 2005, CVTech Group Inc., a Drummondville-based company whose shares are traded on the Toronto Stock Exchange, acquired Thiro, which then became Thirau Ltd. CVTech Group Inc. owns several subsidiaries, with over 1250 employees in the energy sector.

In 2012, the subsidiary Riggs Distler Inc. was founded in Ontario, it will become Thirau Inc. in 2015.

In 2013, Riggs Distler Inc. acquires B.G. High Voltage Systems Limited, supplier of electrical services in Ontario.

In 2014, CVTech Group Inc. changes its name to NAPEC Inc.

In 2016, Thirau Ltd and Thirau Inc. have merged and are now a single entity: Thirau Inc., operating in the Canadian market.