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My home builder said that the following notch in a flange on an I-Joist was acceptable, but I've read that you're never supposed to do so. Is that true?

enter image description here

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Possible duplicate of What are the guidelines for holes in joists? – Mazura Feb 24 at 4:57
So, we'd need the specs on your joists, to see if this violates the manufacturer's specifications of what "penetrations are specifically considered in the design of the member." And the plans for your house and the advice of an on-site structural engineer. So, uh... – Mazura Feb 24 at 5:16
Count yourself lucky. When I bought my house the bathtub -- which plainly had been added after the house was built -- had the drain going completely through the joist, which had been simply cut away entirely so that it was bearing on nothing. "What is holding up the bathtub?" I asked the contractor who was going to remove it as soon as possible. "Hope?" he said. A bathtub weighs a heck of a lot when it is full of water and a person. I am astonished that it did not damage the framing further. – Eric Lippert Feb 24 at 17:08
@EricLippert I found a similar problem with the waste line for a toilet. The joist was simply cut through about two feet away from the rim joist. I jacked up the sagging joist (which runs under the bathroom wall!) and slid in a 4x4 post with a deck-support block under it to spread the load out on the concrete floor of the basement. I never could figure out what the builder was thinking when he just cut the joist that way. – Monty Harder Feb 24 at 17:49
@Mazura -- most holes are through the joist web, if you will, instead of being flange notches like this one. So, not a dupe. – ThreePhaseEel Feb 25 at 0:24
up vote 13 down vote accepted

Point your home builder to page 9 of Weyerhauser's I-joist document here. See the bottom right of the page where it says "DO NOT cut or notch flange"

It is typical of all I-joist manufacturers' installation documents.

As Iggy pointed out, the I-Joist in question needs to be reinforced similar to a cantilever reinforcement.

To fix this, the electrical wires need to be moved to allow the joist to be sandwiched between pieces of OSB, if the pipe is moved, or at the very least have a piece of OSB attached to the backside of this spot. See the I-Joist installation document for how to reinforce for a cantilever.

Then, make sure to back charge the plumber for the repair.

Good luck!

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This is exactly the manufacturer of my joists! Thank you. – gibbo Feb 24 at 21:11

According to this document (PDF), accidental notches in the top flange may not need to be repaired if they meet specific criteria. To determine if a repair is required, we'd need a bit more information, including:

  • The distance from the center of the notch to the end of the beam.
  • The depth of the notch.
  • The specific beam used, including beam height.

If a repair is required, it may be as simple as gluing and nailing on a 2x4 and some backing material.

Diagram showing a repair option

This repair can be placed on either side of the beam, so in your case, it could be done on the side opposite the pipe.

Note that the building code specifically says "unless the effects of such penetrations are specifically considered in the design of the member". This means that the manufacturer of the beam is the one that determines what type and how much damage requires repair.

IRC R502.8.2 Engineered wood products.

Cuts, notches and holes bored in trusses, laminated veneer lumber, gluelaminated members or I-joists are not permitted unless the effects of such penetrations are specifically considered in the design of the member.

If you don't trust the advice of your builder, or simply want a second opinion, you could contact the local building department, and see if they'll come take a look. Contacting a structural engineer is another option, though I'm sure you'll have to pay them for their time.

While damage to these types of beams is concerning, it's better to seek professional assistance, rather than relying on the lunatic rantings of a bunch of dimwits on the internet. Now that you're done reading the lunatic rantings of this dimwit, seek the advice of somebody with a framed piece of paper on their wall.

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From the picture, I think the plumber exceeded the depth of notch indicated in the document you referenced. Even the TJI 210 has a notch depth limit of ¾". I would still opt for the single sided repair option that you indicated and not really worry too much about except for the back charging the plumber part. Lastly, I agree about the lunatic rantings though my OCD won't let me stop. 😉 – ArchonOSX Feb 24 at 13:41

Only if you're a "professional" plumber. Cut twice as much & then measure, hey lookie there just like they did in your place. Seriously no, you're completely right the I's of I-joists are NEVER to be touched nor any holes within 3" of the top or bottom edges. "Responsible" plumbers & builders re-spec a toilet with a deeper stand-off or just pull it out enough to avoid any structural DAMAGE.

Either the entire OSB height (or okay down to the wires) needs to be sandwiched in plywood on both sides for at least 2' before & beyond the error (or as far as you can get to 2'). Or, a single 4' long 2x6 should be bolted to the OSB abutting the offending structural blemish.

IRC R502.8.2 Engineered wood products.

Cuts, notches and holes bored in trusses, laminated veneer lumber, gluelaminated members or I-joists are not permitted unless the effects of such penetrations are specifically considered in the design of the member. – What are the guidelines for holes in joists?

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Mine's based on a best & safest practices, but sure. google.com/?gws_rd=ssl#q=i+joist+penetration – Iggy Feb 24 at 4:42
And to iterate on why you should never cut the flanges, it's because the flanges themselves bear nearly the entire load. – whatsisname Feb 24 at 6:28
Exactly! I-joists are great, but like everything else they have their limitations. The flanges are where the compression & distension forces are specifically focused. – Iggy Feb 24 at 11:20

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