Supporting sagging floor

Discussion in 'Remodel Forum & Blog' started by Weaselpolooza, Jan 14, 2009.

  1. Weaselpolooza

    Weaselpolooza New Member

    Messages:
    17
    Location:
    Michigan
    I have an interior wall that seams to be bearing some load. This is resulting in my floor sagging approximately 3/4" at the base of the Wall. This wall section is about 20' long.

    In my crawl space beneath the wall I poured 4 equally spaced concrete slabs sized 2' x 2' by 10" deep. My plan was to raise the wall by using 2-3 20 foot laminated beams (1.5" wide x 9") backed together and supporting the beam with 4" x 6" posts on each slab.

    Would this be adequate? Any suggestions?

    Thanks
  2. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    Given your situation, anything may be better than nothing, but most of us plumbers cannot give you an engineering "OK". You could contact a general contractor for some advice. Here on the forum, Inspector Jar will be able to offer some advice. Stay tuned.


    Most places would require plans ( signed by a PE ) and a permit.

    If you are planning to jack up the sag at all, that is something which really requires some professional help, because of potential "side effects".
  3. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,928
    Location:
    New England
    To reduce (but not eliminate) the risks of cracking things, you'd need to raise the area slowly over a matter of days to weeks, not minutes or hours. Still, you'll probably have drywall or plaster repairs to do after raising things; just fewer if you let things adjust as you raise it in increments over time.
  4. Scuba_Dave

    Scuba_Dave Extreme DIY Homeowner

    Messages:
    885
    Location:
    South of Boston, MA
    Opening a wall between my new sunroom & kitchen I went to a Lumber Company (not a big box like HD or Lowes) & they sized the LVL beam for me. In addition the one I went to then sends it out for an engineer approval & stamp
    For a ~12' opening I could either go with (3) 11 7/8" or (2) 14"
    The 14" were actually better as far as support & fit better

    For a 24' span in my garage (3) 16" LVL's were required

    I think the 9" may be undersized for 20'
    Sizing depends upon the load, how many stories your house is, snow load, roof load etc. Not something you can just ball park

    Since you want it fixed, better to have it sized so it doesn't start sagging again
  5. frenchie

    frenchie Jack of all trades

    As others have said, there's too many unknows to answer this over the internet. But my first question would be: since this wall apparently wasn't designed to be load-brearing, how did it come to be carrying a load? What else changed?

    Figure out the root causes, so that you don't wind up just treating symptoms.
  6. Weaselpolooza

    Weaselpolooza New Member

    Messages:
    17
    Location:
    Michigan
    The beam will be supported every 6.5' so I think 9" should be plenty.

    My house is a ranch house in the shape of an "L". At the inside corner of the "L" the trusses meet along a 20' length to the other side of the "L". one set of the trusses terminates to a 20' beam in the attic. The wall in question sets about 2' inward from were the trusses terminate in the attic. My guess is that it is absorbing some of the load.

    My thought process is to support the wall from underneath in order to relieve some of the stress that is on the beam in the attic. Perhaps the current beam in the attic is not adquate enough to support the load that it is.
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