Deplazes studied architecture at the ETH in Zurich and graduated in 1988. Along with Valentin Bearth 1988 he founded the architectural firm Bearth + Deplazes Architekten AG. In the same year he received his diploma and was working then as a lecturer for the HTW Chur.

In 1997 Deplazes left his position at the HTL and became a professor of architecture and design at ETH Zurich. From 2005 to 2007 he was head of the department of architecture at the ETH. Currently he lives and works in Zurich and Chur.