enter image description hereI am looking to install two 4x8 overhead storage racks in my garage. Will I compromise the structural integrity of my i-joist, that is, 2"wide × 1 3/8"high × 3/4" to the web if I drill vertically through the flange with a 5/16"×3" Lag Bolt that came with the racks? From what i know the top part of the I-joist is compressed while the bottom is under tension and I can't seem to find any answers on the internet, except when it comes to drill through the web. It's also a 2 story home.

  • I presume this is a wood I-Joist? Who made it, for that matter? Aug 3, 2022 at 2:24
  • Correct its wood. Not sure. On it is written Trus Joist
    – Elvis
    Aug 3, 2022 at 2:33
  • Knowing how an I joist is made, I’m pretty sure the answer is no. But reach out to some manufacturers and ask them. Aug 3, 2022 at 3:02
  • Wouldn't he want to contact the manufacturer of the I-joist instead of "some manufacturers?"
    – RetiredATC
    Aug 3, 2022 at 3:06
  • @RetiredATC I've added a picture to my post above
    – Elvis
    Aug 3, 2022 at 3:10

1 Answer 1


In this publication from TJI it tells you where you can drill and cut the I-joist web. In bold letters it days DO NOT cut flanges.

  • Informative, but the OP is asking about hanging a load from the flange. Aug 3, 2022 at 3:00
  • 1
    I believe he is asking if he can drill through the flange, although maybe I misread it.
    – RetiredATC
    Aug 3, 2022 at 3:03
  • 1
    Agree, but drilling into the flange and loading it is different from cutting the flange. Aug 3, 2022 at 3:04
  • @Aloysius Defenestrate You may be correct. The technical publication has holes in various places of various shapes and groupings in the web of the I-joist. There are no holes in the flanges. An additional note says to not cut or notch the flanges. Based on that, I would not drill a hole in the flange without consulting TJI first. Maybe I'm being too cautious, but the manufacturer is still in business and can be contacted for technical support. What's the downside?
    – RetiredATC
    Aug 3, 2022 at 17:23

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.

Not the answer you're looking for? Browse other questions tagged or ask your own question.