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  1. #1
    Dave Guest

    Default Iron I-beam equivelant to glue lam

    I am going to replace a section of beam in a basement. As per boise cascade the glue lam that they spec will hold 1600plf this is a large beam and headroom would be limited I am considering an iron beam but cannot find any info as to the proper size of the I-beam. It would span 11 feet. Any info is appreciated.

  2. #2
    Tim Guest

    Default Re: Iron I-beam equivelant to glue lam

    You might want to post this question on the "Rough framing" forum also.

  3. #3
    Darren Guest

    Default Re: Iron I-beam equivelant to glue lam

    Dave - any steel supplier should be able to size your I Beam correctly. If not, get a Structural Engineer.

    Steel beams are designated like this: W12x42 would mean a beam with a depth of 12" and 42lbs/lf. (don't use this!!)

    I am an engineer, but not a structural engineer, so I know enough to ask the right questions (and who to ask), but not enough to solve the problem.

    I would give the info about your house rather than the stated load on the wood beam, i.e. basement with load bearing walls on top with some roof load for example.

    One other thought - a built up lam beam may be another option just because of the logistics of installing in an existing basement.

  4. #4
    Paul Fisette Guest

    Default Re: Iron I-beam equivelant to glue lam

    Another option you have -- if you decide that you like using a wood LVL -- is to install a flush beam. Build a temporary supporting system under the floor along each side of the area where you want the 11-foot beam to be installed (a couple of feet away from the center line). Then cut out the floor joists so that the LVL can be slipped up against the subfloor, and fit snugly between the cut ends of the opposing floor joists. Fasten the ends of the joists to the face of the recessed LVL beam with joist hangers and remove the temporary bracing. This should leave you with an acceptable amount of headroom below the beam, since most of the beam will be buried within the floor frame. I have used a Sawsall, but I prefer using a commercial grade jig saw to make the cuts in the joists. You can finish the cuts near the subfloor (where the jig saw foot interferes) with a Sawsall..

  5. #5
    Jim Guest

    Default Re: Iron I-beam equivelant to glue lam

    You would need a W8x21 A36 Steel I-Beam. It is 5-1/4" wide x 8-1/8" deep at 18lb. per foot. Hope this helps.

  6. #6
    Jim Guest

    Default Re: Iron I-beam equivelant to glue lam

    Correction!! That would be 21 lb. per foot for weight.

  7. #7
    Glenn Davis Guest

    Default Re: Iron I-beam equivelant to glue lam

    Jim, I didn't see any information here that would allow you to size a steel beam for this application.

    Are you saying that this is the steel beam that will be equivalent to the gluelam? It is likely that the gluelam is larger than it needs to be. A smaller steel beam may be plenty for the actual load.

    What Dave needs to do is hire an engineer.

  8. #8
    Jim Guest

    Default Re: Iron I-beam equivelant to glue lam


    What I'm saying is that this steel beam spanning 11 ft. will hold 1600# PLF without being laterally supported (side loaded) or it could be side loaded which this would only make things better. The 1600# PLF is the same weather its on a glu-lam or a steel I-Beam. What more info. do you need if he wants something in steel to carry 1600# PLF?

  9. #9
    Glenn A. Davis PE Guest

    Default Re: Iron I-beam equivelant to glue lam

    I'm sorry I didn't make myself clear and it is a small point but it could be important distinction and a smaller steel beam might work and often does.

    Here's why. The owner said Boise Cascade spec'd a beam that had a capacity of 1600 plf. The actual load could have been say 1400 plf. So, lets say that the next smaller I-joist could carry only 1350. Boise Cascade would then spec the next highest size which happended to have a capacity of 1600 which you say is equivalent to a W8x21. But what if a W8x18 would handle 1425 plf (but not 1600). In this case a smaller steel beam would be adequate to carry the hypothetical load but be smaller than the one Boise Cascade spec'd.

    That was my only point. Since I noted that you were an engineer, I thought it was important that we engineers be a little more clear about what we are saying. I'm sure you would agree that it is a better practice to go back to the actual load conditions than to simply select a beam that happended to have the same capacity as one someone else has spec'd.

    What would be even worse is, if Boise Cascade had made a mistake and the beam, then you came along and told the owner what size steel beam he "needed", you'd be liable for the undersized beam.



  10. #10
    Rollie Peschon Guest

    Default Re: Iron I-beam equivelant to glue lam

    I think you did fine Jim. You were asked what size steel beam would it take to carry a load, and you gave an accurate answer. So what if it is capable of carrying more than the actual load. What is wrong with that? If it meets the required loading capabilities, and headroom requirements, how much more can it cost to over size it a tad bit? Not very much in my book. I think the original intention of the post was to ask if anybody knew if this type of system would work, and fit the headroom requirements. If it was found out that it would, then he would be free to pursue a supplyer that would properly size and spec a steel I beam capable of carrying the load.

  11. #11
    Dave Guest

    Default Re: Iron I-beam equivelant to glue lam

    I've been on vacation for a while. Thanks for the responses they are very helpfull. The LVL idea interests me altough it then raises more engineering questions. I appreciate the info.

  12. #12
    JEFF Guest

    Default Re: Iron I-beam equivelant to glue lam

    truss joist has span and load charts available, also there are demo programs available that you can use to calc shear, deflection and bending forces. INSPECTOR JEFF IN JAX

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