Non-Profit Clinic – Seattle, WA 

Floor Collapse Investigation

We performed an investigation of a second floor collapse that occurred during tenant improvement work that was in progress on the first floor below.  We found that the support columns for the floor were only sitting on the plywood floor sheathing with no other framing underneath.  When the infill walls situated between the columns were removed, the columns punched through the floor sheathing and dropped into the crawlspace.  The original building drawings showed that these infill walls were non-bearing; however these walls were actually holding up the entire floor.  The office space above dropped more than a foot along with the people and contents.