Attaching to Engineered Joists - Framers?

Discussion in 'Workshop and Home Improvement' started by MoJ, Mar 8, 2008.

  1. MoJ

    MoJ Moderator

    Joined:
    Oct 24, 2003
    Messages:
    3,255
    I'm finishing my basement and have several places where I need to tie in the tops of non-load bearing walls to the bottom flange boards of the Georgia Pacific engineered I-joists which are supporting the main floor of the house. I'm also boxing in duct work with 2x2 and need to attach it to the same joists. I'm using screws to anchor everything.

    The Georgia Pacific website isn't clear on the proper way to tie in from below. Obviously I'll need to attach only to the flange of the joist and not the vertical support piece. But other than that I'm not sure of how to attach in a manner that doesn't take away from the strength of the joists.

    Anyone have any experience with this?

    Thanks,
    Jason


    Random pic stolen from the web showing the type of I-joist:
    [​IMG]
     
    Last edited: Mar 8, 2008
  2. -Spike-

    -Spike-

    Joined:
    May 26, 2005
    Messages:
    6,164
    Location:
    Phoenix
    I can't imagine there could be a problem with running screws into the bottom of those- or anywhere else you'd like to put screws. It's not like you're dealing with a precision-engineered high-tension product. The natural wood has knots and flaws throughout it, as does the OSB web. A screw here and there isn't gonna compromise the integrity. Of course, that's an amateur's opinion. :D

    -Spike
     
  3. randyr

    randyr

    Joined:
    Jan 15, 2006
    Messages:
    31
    Location:
    Va Beach
    The webbing supplies all the strenght for the joist. The 2x2s on the top and bottom just provide a surface for attaching floorboards or cielings to. You will pretty much have to cut out holes in the webbing to run utilities through, just don't cut out the whole piece of webbing. The builder of my house cut out enough webbing to run 8x8 ducting through (that would be the entire height of the joist's webbing) and caused the floors to sag and squeak. It was a real PITA to reinforce those joists and fix the floors.

    I would just go ahead and attach the wall header. Screwing into the joists will not affect their strength. You should have no issues
     
  4. osagecruiser

    osagecruiser

    Joined:
    Nov 11, 2004
    Messages:
    2,255
    Location:
    Kansas!
    you should have no adverse affects screwing your top plates to the i joist 2x...i have done it many times with no problems

    osagecruiser
     
  5. haystax

    haystax

    Joined:
    Mar 9, 2004
    Messages:
    1,260
    Location:
    Diamond Valley, Nevada
    I am about to have a similar discussion with my contractor about tying a non-structural basement partition to load bearing TJI joist - do you want to allow things to move and isolate one from another or is it better to tie the things together so they move as one unit?

    I am leaning towards a shim between the truss flange and top plate and a 16d through nail from plate into flange above.

    Are you planning to drywall the ceilings? My main concern is for drywall cracks as the building settles as it is new construction rather than a finished home with a basement finishing after the rest of the home has settled in.
     
  6. MoJ

    MoJ Moderator

    Joined:
    Oct 24, 2003
    Messages:
    3,255
    Thanks everyone for all the replies!

    haystax - I plan on drywall for the ceilings. I haven't had any trouble with anything cracking it the past. The last house had solid joists and I finished it about a year after building. The current one is about 6 mos old. Some of the experts may give you a better answer but I usually just tie everything together.
     
  7. Tunnelratt

    Tunnelratt

    Joined:
    Apr 23, 2006
    Messages:
    336
    Location:
    So Cal
    Connecting the bottom cord of a TJI to an intermediate wall can be done by toe nailing or with a truss clip, it is just there to keep the joist from floating, if you are worried about settling and cracking of the drywall, because you have large un supported spans, you can use R.C. resiliant channel / hat channel, it is a metal product that screws on to the bottom of the joists perpendicular to the way the joists are installed, then the drywall is attached to the R.C., it allows things to flex a bit.
    If the design of your floor system is such that it has bearing points in the design, adding another location that the floor settles will not be an issue, unless it creates a crown.
    If all you are looking for is an answer to " can I attach to the bottom cord of a TJI"? the answer is yes
     
  8. RHINO

    RHINO

    Joined:
    Dec 23, 2003
    Messages:
    3,759
    Location:
    valley of the sunstroke, AZ
    as mentioned treat it as regular old lumber, nail, screw, whatever.

    take the hint from randyr, if you are going to cut holes in the webbing bigger than the provided punch-outs get the details from your local code, you can cut holes but i dont remember off the top of my head the numbers.
     
  9. EricG

    EricG

    Joined:
    Jul 12, 2006
    Messages:
    1,813
    Location:
    Colorado Springs, CO
    And remember that holes in the web of TJI are one thing, holes in microlam beams like the in that picture are something else entirely. They are much pickier about *any* holes in microlam beams - BTDT, still waiting on the letter from my engineer :doh:
     
  10. Toyo FJ40

    Toyo FJ40 SILVER Star

    Joined:
    Dec 7, 2004
    Messages:
    1,022
    Location:
    Eastern PA.
    Well I know you can't put large holes (bigger than 1 1/2" )closer than 3 feet from end or support of a TJI (found this out the hard way)

    I was told that I could put 1" holes in a microlam anywhere there was a support column under it (which wasn't anywhere near where I needed them)

    Kevin
     
  11. EricG

    EricG

    Joined:
    Jul 12, 2006
    Messages:
    1,813
    Location:
    Colorado Springs, CO
    What I've been told for holes in microlam is that they must be in the center 1/3 of the depth, and center 1/3 of the span. Not sure how big, my issue was for a 3/4" pipe and another two holes about the same size for CAT5 & ROMEX.
     

  12. Toyo FJ40

    Toyo FJ40 SILVER Star

    Joined:
    Dec 7, 2004
    Messages:
    1,022
    Location:
    Eastern PA.
    This job was strange, The engineer designed the house to span an existing foundation and 1st floor deck so there was microlams on top of every wall on the first floor. I had a hell of a time running plumbing so I had to drill through the beams in a few places. The engineer told me any place that there was a support under the microlam to the foundation or support beam in the basement then I could drill a hole in the beam. I had to call the manufacturer on another job and was told the same thing as you about the 3/4" holes. I guess it would depend on your load and the size of the beam weather or not you could do 1" for a 3/4" pipe.

    Kevin
     

Share This Page