Ervi completed his most notable and well-known works during the post-war reconstruction period and later in the 1950s during the development of Finland's modern construction industry.
Ervi was among the pioneers in the use of concrete elements in Finnish architecture while working on the design of the University of Helsinki's Porthania building in 1949.
He also designed hydro power plants and residential areas for the company's employees for Oulujoki Oy.
One of Finland's largest hydro power plants in Pyhäkoski was designed by Ervi, as was nearly all of the nearby settlement, Leppiniemi.
He also designed many of its most recognizable buildings, including the Tapiola Central Tower, shopping centers Tapiontori and Heikintori, and the swimming hall.