The NFIRS Incident Type for a structure fire (a building fire) is 111. (One hundred and eleven.)
Note: Code 111 excludes “confined fires”, e.g. chimney fires or contained cooking fires. If those confined fires extend into the structure, they are no longer confined, and are coded as a full building fire.
See all the NFIRS fire incident types to determine the correct NFIRS code for your incident.