A building inspector being informed that a structure or anything appurtenant thereto is unsafe shall inspect the same. If it appears to be unsafe, he or she shall forthwith notify, in writing, the owner, agent, or person having an interest therein to remove it or make it safe and secure. If it appears that such structure would be especially unsafe in case of fire, it shall be deemed dangerous and the inspector may affix in a conspicuous place upon its exterior walls a notice of its dangerous condition, which shall not be removed or defaced without authority from him or her.