Chloride and carbonation induced corrosion in reinforced concrete structures poses a significant threat to the durability of these materials. This study focuses on the corrosion behavior of a parking garage ceiling exposed to deicing salts. Potential measurements including measurements of chloride content and carbonation depth were conducted from the upper and lower side of a ceiling. Comparing the cumulative frequency of the potential values shows that the ceiling top view has lower potential values than the ceiling soffit. This can be explained by generally higher moisture content, higher chloride content and lower carbonation depth in the top view than in the soffit. These results lead to the assumption that the degree of corrosion is higher at the top view. However, the most severe corrosion attack has been found at the bottom view of the ceiling, namely in the region of separating cracks. Due to the combination of high chloride and moisture content, chloride ingress can easily access the lower part of the ceiling through these cracks and penetrate into the concrete. Only little corrosion can be found in regions of the soffit without cracks. There, the carbonation depth is also high, but as concrete moisture and chloride content are significantly lower, the corrosion attack is less pronounced. The study reveals that these separating cracks are critical sites where corrosion attack is most pronounced. Moreover, if the corrosion attack is severe in these cracks a structural assessment of ceiling might be necessary.