Isaac Plas was a son of Arie Joseph Plas and Vrouwtje Sons. He married in Zaandam on 4 May 1910 to Marianne Schenkkan, who moved to "Het Apeldoornsche Bos" on 21 October 1930. The couple had three children: Vrouwtje, Lena and Arie.
Municipal Archive of Amsterdam, archive card of Isaac Plas.