Bridging is often required in floors or roofs when solid-sawn lumber joists are used. This addition provides lateral support to twisted joists to help maintain a vertical orientation. It also facilitates load sharing. Load sharing can be important because of the large variation in material properties found between joists within any solid-sawn lumber grade-group.
Trus Joist® TJI® joists are made with no observable twist and have minimal material variation between joists within any specification group. Consequently, they do not see any significant benefit from bridging. Our code report (ICC ESR-1153) specifically states that bridging is not required for floor and roof TJI joist applications. Weyerhaeuser has found that the addition of bridging does little to improve floor performance and may create squeaks. It is the policy of Weyerhaeuser to recommend against installation of bridging unless an unusual condition exists that would be improved by this addition.