What kind of information is provided on the joist tag and is it helpful in identifying the capacity of the joist?
Typically, the joist tag provides information that is useful to the erector in matching a particular joist in the field to a location on the placing plan. If the placing plan or approved field use drawings from the joist manufacturer are available, then the tag information could be useful. If plans are not available, it is possible that the manufacturer may still have helpful information. When all else fails, contact the manufacturer.
Are bearing seat depths helpful in determining the joist series?
Typical seat depth for short span joists (SJ, S, J, H & K) is 2 ½”. Typical seat depth for long span joists (Longspan, L, LA, LJ, DLJ, LH, DLH) is 5″. For DLH-Series with chord section 18 through 25, the seat depth is 7 ½”.