Engineered Wood I-Joists as Tension Members

By Dan Martel, P.E. | June 1, 2022

Engineering wood I-joists (TJI, BCI, AJS, etc…) are a popular choice for floor framing members in wood-frame construction, and we like them for the same reason others do: they are very efficient structural members, meaning they carry a lot of loads compared to their own weight. And since they are made from engineered wood products, they are straighter and truer than natural, conventional wood (2x lumber). We often specify them as floor joists, and when screwed and glued to the floor sheathing, they provide excellent resistance to vibrations often caused when people walk across a floor.

While they are great under bending conditions, they are less efficient resisting tensile loads. Some manufacturers, such as Weyerhaeuser, have tested their joists and determined that they are strong enough to use as tension ties for common gable roofs, so long as the ends are blocked as detailed in one of their technical bulletins (click here to read).

With that in mind, this is not true for all I-joist brands – some explicitly say that their product may not be used if subjected to tension. Before using I-joists, be sure to know if and how they can be used as a tension member! Of course, if you have any questions, give one of our engineers a call today!

2 thoughts on “Engineered Wood I-Joists as Tension Members

  1. Adam

    Good morning. Are TJI (230) equivalent to BCI (60) – can one be used instead of the other under the same conditions (span, etc.)?

    Reply
    1. Brian Ki, P.E.

      Great question! Lumber suppliers have their own proprietary engineered wood products they each use. TJI is from Weyerhaeuser and BCI is from Boise Cascade. In most conditions, each are interchangeable assuming the dimensions and properties match. Most building material suppliers usually carry one lumber company and not both. They can check with your specific instance and see if the joists are interchangeable.

      Reply

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