In 1963, extensive and urgently needed renovation work began at the Sennhof. At that time, as many as eight inmates were accommodated together in dormitories with only one toilet and a small sink each. The part of the building facing Sennhofstrasse was expanded, including a residence for the administrator and chief overseer. The most noticeable change was the construction of the new, slightly curved cell block, which still stands today: the arch-shaped block with a hostel and KostBar.

Around 1970, new workshops, recreational and common areas for the inmates, as well as additional cells for women, were built. In the early 1990s, there were further significant construction projects. Firstly, security at the main entrance had not been guaranteed until then because there was no security checkpoint; this posed an irresponsible risk, also for the secretariat. Secondly, visitor rooms had to be expanded as new guidelines allowed for more frequent visiting hours. Additionally, measures were taken to reduce the risk of escape in various areas.