Like many i-joist manufacturers, Weyerhaeuser assumes composite action with glue-nailed subfloor panels installed overtop the TJI floor joists as outlined in our Trus Joist® TJI® Joist Specifier's guide (TJ-4000). However, Weyerhaeuser does not require the subfloor panels to be glued to the TJI floor joists. When subfloor adhesive is not applied, allowable spans shall be reduced by 6ʺ for nailed only connection and 12ʺ for proprietary fasteners as indicated in TJ-4000 to account for the reduction in stiffness from these alternate connection methods.
The elimination of glue may affect the floor system performance. The resulting TJ-Pro™ Rating with a nailed only subfloor attachment can be checked in Weyerhaeuser's Forte®WEB design software, under the floor performance tab. Nailed only subfloor connections may increase the potential for floor noise. For additional information, reference Technical Resource Sheet #9009, "Prevention & Repair of Floor System Squeaks".
For floor systems that have been specified using a glue-nailed subfloor connection by the Design of Record (DOR), omitting the subfloor adhesive must be reviewed and approved by the DOR prior to construction. Unblocked diaphragm capacities may require further evaluation if the DOR took an increase for installation with subfloor adhesive that meets Type P/O per ASTM-D3498-19. More information can be found on Table 2 of the TJI® code report, ESR-1153.
Weyerhaeuser's Trus Joist® TJI® joist product warranty applies whether subfloor adhesive is used or not.