In late 1940, the manor began to focus on oil crops, getting rid of livestock entirely by 1951. Sanmark sold parcels of land from the manorial estate between 1937 and 1942, to become a housing area for the district of Vaarala, in 1950, among others, to Karl Fazer Ltd in 1960, Keskus-Sato Ltd, to be developed into Hakunila district’s new housing area.
Per-Kasten died in 1983, and the ownership of the manor passed to his heirs. The Sanmarks used Håkansböle as a holiday home up until the 1990s. The manor was put up for sale in the autumn of 2002 by the heirs. The city of Vantaa decided to purchase the manor, along with its grounds, on 18 April 2005, and it came under the ownership of the city in August of the same year.