Called Hans in his youth, he studied art and architecture, and in 1925 traveled to Paris, and worked with prominent modern architects producing a handful of villas of his own until 1937.

[1] In 1937 Welz emigrated to South Africa with his wife the Danish journalist, Inger Christensen, and their young son, and began work as an architect at the University of the Witwatersrand, where he designed the entrance foyer of the Great Hall and the Institute for Geophysical Research.

[2] Although Fisher was a fan of Loos' modern approach, he relied on Welz to put the theories into practice and gave him free rein of Maison Dubin (1928).

Fisher, unlike many architects depending on a junior, allowed Welz to take much of the credit and the building was right next door to Le Corbusier's Villa Cook (1926).

In 1947 he was awarded the Silver Medal of the South African Academy for Arts and Science for his picture Earthenware and cupboard door.