lally columns

Discussion in 'Remodel Forum & Blog' started by smatarazzo, Sep 14, 2009.

  1. smatarazzo

    smatarazzo New Member

    Messages:
    1
    Location:
    ny
    help..lally columns

    I want to replace a lally column in my basement. the columns are spaced about 5'5" apart and i want to take out the center column (of 3). My plan was to take 2 more columns and place them just inside of the 2 outer ones, on top of these columns I would put an 8x8 beam to span the 10' gap that existed. My main beam consists of 6 2 x 12's. I have lot of people telling me that leaving the 11 foot gap would be fine b/c of my existing beam, and that i dont have to put anything there at all, but i think just to be safe the 8x8 supported by the 2 columns will make up for the absence of the middle one i pull out. will my plan work?
    Last edited: Sep 14, 2009
  2. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,641
    Location:
    Cave Creek, Arizona
    lally

    Are you going to take the advice of someone who has NEVER seen your installation, and has NO IDEA why the lallies were installed that way? It seems so unusual that there may be some good reason for it and the only way to be sure is to have a structural engineer check it out.
  3. Scuba_Dave

    Scuba_Dave Extreme DIY Homeowner

    Messages:
    885
    Location:
    South of Boston, MA
    Doubling the span distance without knowing the load on the beam is not a good idea
    If the exisiting beams could span 11' they would have probably built it that way
    As hj said, you can't guess at this, you need to have an engineer verify the loads & beam required
  4. Lakee911

    Lakee911 I&C Engineer (mostly WWTP)

    Messages:
    1,328
    Location:
    Columbus, OH
    Post details about your house, spans, materials, walls, loads, etc and someone can help.

    6-2x12's seems like a fairly large beam to me...must be a big load...
  5. seaofnames

    seaofnames DIY Senior Member

    Messages:
    162
    Location:
    Mission, BC
    As stated. Get an engineer to look at it.

    Then get an engineered beam!! Much stronger than just 8x8 or 6 2x12s or any of that jazz. Engineered beams are the way to go for any kind of major structural change.
  6. Lakee911

    Lakee911 I&C Engineer (mostly WWTP)

    Messages:
    1,328
    Location:
    Columbus, OH
    If it indeed has that sort of load, I would put in a steel beam probably.
  7. seaofnames

    seaofnames DIY Senior Member

    Messages:
    162
    Location:
    Mission, BC
    I didnt even think about that!! Steel is awesome.
  8. loafer

    loafer Mechanical Engineer

    Messages:
    49
    Location:
    Maine
    By doubling the span, you will decrease the stiffness of that beam by a factor of 8.
  9. Lakee911

    Lakee911 I&C Engineer (mostly WWTP)

    Messages:
    1,328
    Location:
    Columbus, OH
    If it doesn't fail first...
  10. loafer

    loafer Mechanical Engineer

    Messages:
    49
    Location:
    Maine
    Well, if we assume that the 6, 2x12 beam is required over your 5.5' span for stiffness purposes, then it is fairly easy to calculate the required steel beam that will span 11’ and still meet the same stiffness requirement. According to my figures, I come up with a W12x35 beam as a suitable replacement, which is a wide flanged I beam that is 12†deep and weighs in at 35lb/ft. Other steel beam options are possible, providing the minimum moment if inertia of 285in**4 is met.

    My calculations are based on maintaining an equivalent stiffness from the 5.5’ span to the 11’ span. In other words, if your existing beam has a deflection criteria of L/500, the maximum deflection is 0.011in, the same deflection criteria at the 11’ span will allow for a 0.022in deflection.

    I would not start this project w/o first having an engineer come out and look at your particular situation though.
  11. toolaholic

    toolaholic General Contractor Carpenter

    Messages:
    874
    Location:
    Marin Co. Ca.
    Take this with a grain of salt . Bolt 2x8 channel iron on either side of the beam
    Place 1/2" bolts 32" on center staggered. One up one down. Now You've increased the point load on the column footings. This is My 49 th year building homes. You need and experienced carpenter , a structual Eng. and a building permit. But that ain't gonna happen,is it? If this don't work out SUE DUNBAR,
    He's the only one who has any money here!:D
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