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  1. #1
    Join Date
    May 2010
    Posts
    65

    Question Another sistering floor joists question...

    I've seen several threads, on several sites, but none quite seem to answer my question.

    Anyway, as a preamble here are some specs -

    Local code - IBC 2003
    2x10 joists, 16" on center, 14' span, yellow pine (from what I can tell)

    Pretty much every joist has been bored out of code. Each joist has a half inch hole within 2 inches (some less than 1 inch) of the bottom of the joist, in the center third of the span. One joist has cracked directly below the hole.

    Obviously the very best way would be to sister the joist between the center beam and the sill plate, but that's a big job for the sake of half inch holes and there are numerous challenges in the way. I'm presuming though that it's guaranteed up to code.

    So, onto the questions.

    1. Other than the one already mentioned are there code-specified fixes?

    2. I could get a 6' 2x10 up there with relative ease, overlapping 3' either side of the fix. I'd attach with construction adhesive and lag bolts or 3" framing nails. The theory being that although it wouldn't remove any load from the joist, it would increase the tensile strength at the bottom.
    > Does that sound accurate and viable?
    > Is it acceptable to code?

    3. Are there any reinforcement products on the market, and what sort of $ are we talking about?

    4. Am I making a mountain of a molehill?


    Thank you all very much in advance for your advice.

  2. #2
    Join Date
    May 2010
    Posts
    65

    Default Re: Another sistering floor joists question...

    I should add that there is an existing suspended ceiling, so attaching 2x4s to the bottom of the joists is not an option (or at least not a desirable one). I'll be doing this in the unfinished portion of the basement, however.

  3. #3
    Join Date
    Jan 2014
    Posts
    1

    Default Re: Another sistering floor joists question...

    I have an issue very similar to this one - sorry to not see a reply.

    My obstacle is that electrical (which like yours is in a 1" dia hole less than 2" from bottom of 2x8) is forcing me to put a 6" notch (coming from top) in the 2x8 I plan to sister. I know this isn't preferred method, but if possible I would like to avoid calling out an electrician to move/move back the wires.

    Any other options?
    Is this something an inspector will flag when I go to sell my home? I really don't think this is a big structural problem but others may think differently.

    I have a diagram but wouldn't allow me to upload. Thanks for any input.

    Niles

  4. #4
    Join Date
    Jul 2010
    Location
    SoCal
    Posts
    5,089

    Default Re: Another sistering floor joists question...

    Quote Originally Posted by niles View Post
    I have an issue very similar to this one - sorry to not see a reply.

    My obstacle is that electrical (which like yours is in a 1" dia hole less than 2" from bottom of 2x8) is forcing me to put a 6" notch (coming from top) in the 2x8 I plan to sister. I know this isn't preferred method, but if possible I would like to avoid calling out an electrician to move/move back the wires.

    Any other options?
    Is this something an inspector will flag when I go to sell my home? I really don't think this is a big structural problem but others may think differently.

    I have a diagram but wouldn't allow me to upload. Thanks for any input.

    Niles
    You can not notch 6" off a 2x8 joist.

  5. #5
    Join Date
    Jan 2008
    Posts
    1,101

    Default Re: Another sistering floor joists question...

    "Sistering" isn't a cure-all but if done correctly can bring an out-of-spec joist back into code compliance if there;s enough space. A more sensible option may be to break up the span with a support beam, thus changing the relationship of non-compliant holes to their position regards their support. Wiring is usually easy to move but if you're not comfortable working around it, get a licensed electrician involved with the project. And any time a sistered joist is seen by a knowledgeable buyer or inspector, they're going to want to know why it was done, and whether the repair was done correctly or not, so it must be done correctly or it will bite you later on.

    While I do agree with the general rule of thirds and sixths, if the hole is small enough and not far from it's correct position and it's not giving problems, you may be better off just leaving it alone. But if there are problems or questions of strength, it's usually easier to fix now than wait for more sagging to happen later. This is also one area where an engineer may be worth their cost, as you may not need to sister a whole joist, but only a portion of it, and having their drawing will clear any future buyer's concerns.

    Phil

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