In July 1844, while living in Neustadt an der Aisch, Schwaab had a daughter, named Elize Auguste Catharine, with Elizabethe Fuchs.

He married Matilda Vonsinem on October 22, 1853, in Richmond County, Georgia, with whom he had three children: Otto G. (1856–1900), Gustavus Adolph (1860–1940) and Mathilda Bryant (1869–1951).

All of the children were born in the U.S.[2] One of Schwaab's first designs upon arriving in the United States was Savannah's Gray Building (1856), on what was then known as Broad Street.

[1] Five years later, he entered into an architectural partnership with fellow German, Martin Philip Muller (1829–1876),[1][6][7] with whom he designed the final building to house Savannah's City Market.

The city eventually decided to use existing sewer lines to connect with the Bilbo Canal, the course of which ran behind the Atlantic and Gulf Railroad depot to the southeast of Savannah.