The article presents the results of non-destructive testing and analyses carried out for a brick masonry building from the 19th century, which has many irregularities that involve a lack of inspections and tests of its technical condition for many years, as well as a failure to carry out necessary repairs. The conducted organoleptic tests enabled the most significant building damage to be indicated, and its causes were determined on the basis of the results of non-destructive tests and analyses. These causes include mainly wall cracks, ceiling deflections and excessive dampness. It also contains the relationships, which were developed using non-destructive dielectric and resistive methods when testing the moisture content of the brick walls. These results may be useful for other researchers dealing with brick masonry buildings from a similar period of time. The authors' intention was to present the existing poor technical condition of the brick masonry building and indicate its causes, as well as to present that a lack of appropriate maintenance can lead to a situation in which the life or health of residents is threatened.