The Teilum building housing the Department of Forensic Medicine at the University of Copenhagen was renovated in 2021/22. All windows were replaced, and the heating system was upgraded. During the renovation, the usual measures to prevent PCR products from escaping the post-PCR laboratories could not be maintained, since construction workers had to move in and out of the rooms carrying tools and debris. Instead, new measures were introduced, that included 1) the construction of a changing room for the workers with immediate access to the post-PCR laboratories, 2) clothing and shoes for the workers, that should only be worn inside the post-PCR laboratories, and 3) strict limitations on the areas the workers could enter, while renovating the post-PCR laboratories. Samples were taken before, during and after the renovation to monitor the possible spread of PCR products from the post-PCR areas. Mixtures of gDNA and PCR products were detected in only three of the 303 samples. All three samples were collected from the post-PCR areas prior to the renovation began, which indicated that the renovation did not cause wide-spread contamination of PCR products.