Josh Kiermaier established Kastell Building in 2012 as a part time gig. In 2017 with the addition of business partner James Smith, Kastell Building opened for full time trading. In three short years Kastell has grown from its home in a spare room in Josh's parents house to a company with 25 full time staff and is a contractor of choice for developers and builders.

Kastell have worked on projects ranging from premium retail brands to some of Canberra's most iconic developments and are one of Canberra's most exciting construction companies.