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Thread: Floor Joists

  1. #1
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    Default Floor Joists

    Can a home have I beam joists and floor trusses mixed in together? I had a question on my exam with a picture of an I beam joist and a floor truss holding up the floor and it asked if it was ok. I looked everywhere online and couldn't find anything.

    Oh and if anyone knows if a pitch is required on a concrete landing outside I couldn't find that one either lol

    thanks

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  2. #2
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    Default Re: Floor Joists

    Of course you can mix I beams and wood joists. Joists would typically handle the floor load. I beams would handle mid span support loads or bearing loads above.
    Based on your description the wood joist may have been there just to handle the floor load. The I beam may have been there as a load bearing support for a wall above that was supporting the 2nd floor, roof or some component that needed additional support.
    I don't remember if there is a slope requirement and don't have time to look it up. Someone will know more readily.

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  3. #3
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    Default Re: Floor Joists

    Quote Originally Posted by Markus Keller View Post
    Of course you can mix I beams and wood joists. Joists would typically handle the floor load. I beams would handle mid span support loads or bearing loads above.
    Based on your description the wood joist may have been there just to handle the floor load. The I beam may have been there as a load bearing support for a wall above that was supporting the 2nd floor, roof or some component that needed additional support.
    I don't remember if there is a slope requirement and don't have time to look it up. Someone will know more readily.


    thank you very much it was an exam question that I couldn't find


  4. #4
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    Default Re: Floor Joists

    Quote Originally Posted by Aaron Scheuerer View Post
    Can a home have I beam joists and floor trusses mixed in together? I had a question on my exam with a picture of an I beam joist and a floor truss holding up the floor and it asked if it was ok. I looked everywhere online and couldn't find anything.

    Oh and if anyone knows if a pitch is required on a concrete landing outside I couldn't find that one either lol

    thanks

    R311.3 Floors and landings at exterior doors. There shall
    be a landing or floor on each side of each exterior door. The
    width of each landing shall not be less than the door served.
    Every landing shall have a minimum dimension of 36 inches
    (914 mm) measured in the direction of travel. Exterior landings
    shall be permitted to have a slope not to exceed 1/4 unit
    vertical in 12 units horizontal (2-percent).


  5. #5
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    Default Re: Floor Joists

    Awesome thank you so much I couldn't find that anywhere!!!

    - - - Updated - - -

    Quote Originally Posted by Marc M View Post

    R311.3 Floors and landings at exterior doors. There shall
    be a landing or floor on each side of each exterior door. The
    width of each landing shall not be less than the door served.
    Every landing shall have a minimum dimension of 36 inches
    (914 mm) measured in the direction of travel. Exterior landings
    shall be permitted to have a slope not to exceed 1/4 unit
    vertical in 12 units horizontal (2-percent).
    So where is this from ? How can I get it ?


  6. #6
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    Default Re: Floor Joists

    Quote Originally Posted by Aaron Scheuerer View Post
    Can a home have I beam joists and floor trusses mixed in together? I had a question on my exam with a picture of an I beam joist and a floor truss holding up the floor and it asked if it was ok. I looked everywhere online and couldn't find anything.

    Oh and if anyone knows if a pitch is required on a concrete landing outside I couldn't find that one either lol
    You state "I beam joist" and I assume you are referring to the engineered wood I-joists like TJI rather than a metal I beam. I cannot say for sure, but I would guess that is not allowed. They are an engineered system and it's unlikely that two different manufactures would allow for that in their installation instructions or would be willing to collaborate in that way. At least not without a lot of money changing hands.

    Looks like Marc's reference is either from the California Residential Code or the International Residential Code.

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  7. #7

    Default Re: Floor Joists

    Quote Originally Posted by Gunnar Alquist View Post
    You state "I beam joist" and I assume you are referring to the engineered wood I-joists like TJI rather than a metal I beam. I cannot say for sure, but I would guess that is not allowed. They are an engineered system and it's unlikely that two different manufactures would allow for that in their installation instructions or would be willing to collaborate in that way. At least not without a lot of money changing hands.

    Looks like Marc's reference is either from the California Residential Code or the International Residential Code.
    I agree. Terminology would normally read 'engineered' or 'sawn' lumber as used in joisting configurations. A beam reference is for 'header' or 'girder' type beams that support respectively either 'ceiling' or 'floor' type joists.
    The notable difference between the two joisting systems is the permitted span distances that require different restrictions on where hole locations are allowed for joist deflection maximums at midspan or cantilever supported locations.


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