Sagging garage

Discussion in 'Framing and Foundation' started by bdisking, Apr 4, 2014.

  1. Apr 4, 2014 #1

    bdisking

    bdisking

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    I have an old garage from around 1900 and it is sinking mainly on one side. But it has no concrete foundation it is just wood flat on the ground.it is a big garage 30feet by 20 feet and 2 story's tall. First thing is how do I get it level then how do I keep it supported. Any help would be great thanks.
     
  2. Apr 4, 2014 #2

    nealtw

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    Welcome to the site. We will need to know how it is constucted and there will be lots of question before you get answers to this. Can you post some picture.
    It is important to figure out if it is built like a house or like a barn, how the upper floor is attached and supported and how bad it has sagged.
     
  3. Apr 4, 2014 #3

    Wuzzat?

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    http://www.google.com/search?q=heli...lue.com%2Ffoundation-helical-pier.htm;300;462
    ?

    You'll need to estimate or calculate the weight of this building. 20 x 30 x 120 lbs/SF(?) = 72,000 lbs = 36 tons, so each corner weighs 9 tons.
    $75 and up for a bottle jack.

    How far do you need to lift it? If it's 1 ft and you can somehow put 1 hp into this jack handle then it'll take you 30 seconds.
    Take at least an hour and check frequently if the building walls are being twisted out of shape. Taking several days is probably safer.
     
    Last edited: Apr 4, 2014
  4. Apr 11, 2014 #4

    carnuck

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    How are the timbers inside? Is it dirt floor?
     
  5. Apr 12, 2014 #5

    bdisking

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    The sill plates are like a 4x4, studs are 2x4 I haven't tore up any floor boards to see how its built but I can if needed

    1397322330037.jpg

    1397322341525.jpg

    1397322357135.jpg
     
  6. Apr 12, 2014 #6

    Wuzzat?

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    If the sill plates are bent from decay or structural failure then you have real problems and even if they're not a 9 ton concentrated load or a 9 ton distributed load will bend a 4x4 that is not uniformly supported by the ground.

    This thing should be raised by at least three jacks with one at the corner. But, if you sight along the sill plates and they're high in the middle it's the corners where the soil has subsided.

    Since there's no drywall you can see everything and make a pretty good estimate of the weight of this structure.
    A default value for the density of softwood is 35 lbs/cu ft. How many pieces of what length and width and depth are there?

    As to cause, maybe you can find it here
    http://en.wikipedia.org/wiki/Subsidence
     
    Last edited: Apr 13, 2014
  7. Apr 13, 2014 #7

    nealtw

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    I would be surprized if this thing stude here for that many years with out a foundation, I would like to see you dig around a little and see what's under there.
    You will likey have some bad floor joists under the floor too, if it's built close to the ground.
    The fix for one side goes something like this.
    Remove enough floor sheeting to dig down and install a concrete footing about 18" square and eight inches deep on solid undisturbed soil, how ever deep that is.
    Do this at each end of the wall and in the middle of the wall.
    If the corners of the building are level with each other, build cribbing on the corner footing to about 2ft above the floor.
    You build 2 beams out of something like 4 2x12 long enough to reach from the corner to the center where the jack will be.
    In the center you place the jack with about a 2ft peice of 6x6 steel H beam with a cradle welded to it to fit the top of the jack to keep it centered while jacking.
    On top of that fits the two beams. You set the jack height so the beam is reasonable the same height from the floor above and build a temp wall from the beam to the floor above.
    With angle braces on the wall from high to low so it won't rack and braces from the new wall to old wall and from new wall on an angle to the floor above.
    In other words you brace the crap out of it so everything stays together when it is being lifted.
    If you find rotton floor joist or you are afraid they won't go up with the rest of the building you tie the two floors together with more braces.
    The one thing about hydrolic jacks is, if it's not big enough it won't lift it.
    You also set up two spots where you can shim as you go so if you have to reposition or you have a failure, you have captured all gains.
     
  8. Apr 13, 2014 #8

    Wuzzat?

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    Last edited: Apr 13, 2014
    nealtw and slownsteady like this.
  9. Apr 15, 2014 #9

    bdisking

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    This is how it looks underneath all the wood looks surprisingly good except what you see at the top of the picture were the sill is rotted out only on the side that is sagging.

    1397520445465.jpg
     
  10. Apr 15, 2014 #10

    nealtw

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    Is the photo from the back or from under the window?
     
  11. Apr 15, 2014 #11

    bdisking

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    Under the window
     
  12. Apr 15, 2014 #12

    nealtw

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    Ok that's just wrong, I have lost faith in the oldtimers that built this.
    You have the weight of 1/4 of the roof, 1/4 of the upper floor, 1/4 of the lower floor and 1/2 of the wall all held up by the outside floor joists.
    Jacking it up would be the same but longer as these peices will have to bend back to place so lifting may be as slow as 1/8 to 1/4 inch per day.
    Once up you would be able to work on the foundation and any repairs along that side.
    Then you might consider the same proceedure for the rest of the walls with some other considerations.
     
  13. Apr 15, 2014 #13

    Wuzzat?

    Wuzzat?

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    The electric motor from a clock probably has enough horsepower to do this. :D
     
  14. Apr 16, 2014 #14

    nealtw

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    Not likely............................
     
  15. Apr 16, 2014 #15

    Wuzzat?

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    Yeah, I ran the numbers after I posted that.
    It brings up the question whether anyone makes jacks run by motors through a gear train that runs day and night at the extremely slow speeds you posted.
    That way the OP just sets it up and monitors the building once or twice per day, for what might take a month.

    And the low power means the whole setup could be run by batteries. I think I'll start hiring illegals to produce this thing. :D
     
    Last edited: Apr 16, 2014
  16. Apr 16, 2014 #16

    nealtw

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    Check it twice a day or crank the handle twice a day, either way you want to install shims.:p
     
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  17. Apr 17, 2014 #17

    Wuzzat?

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    and ask some questions about this.

    The main reason to use 30 days vs. 30 seconds to raise this building is to let the soil resettle and accommodate the new angle of the building floor?

    As the soil resettles, the downward force on the jacks will decrease because the resettling soil acts like a very viscous fluid?

    The wood & fasteners in the building don't care about taking 30 seconds or taking 10 years?

    What symptoms may show up during this process and what are the fixes?

    Any other considerations for a project like this?
     
    Last edited: Apr 17, 2014
  18. Apr 17, 2014 #18

    nealtw

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    If you put in good footings to jack on soil settlement is out of the picture.
    That side of the building looks like it has never had support. Take the total sag, lets say 4 inches and you devide that by say 100 years and you get some idea how long it took to slump 1/8"
    If nails and other fastners didn't do there job it would have fallen down years ago and they will try to do there job when you want to push the other way.
    If you had a jack big enough the fear would be that you could over jack the center and if the building resisted you might lift the whole side on one jack, very dangerous.

    A few years ago I helped a friend lift the back half of his house to near level. A hand full of 25 ton jacks. 1/8" was easy and the jack would not go 1/4". Another friend showed up and thought he could get more, This jack was cribbed on the basement floor and when the floor broke so did his arm.
    Any time you do work like this a good feel and wise fear is in order.
     
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  19. Apr 17, 2014 #19

    Wuzzat?

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    Also a jack that registers the force it is pushing against. A steep increase in force means rethinking the project. Since civil engineers are building from scratch they may not have to worry about this.

    This thread may now save some arms and some lives.
     
  20. Apr 17, 2014 #20

    bud16415

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    I have said before I think in cases like this and as Neal has just pointed out perfection shouldn’t be the goal. I have always felt the key word foremost should be stabilization and then correction. If you take a gob of silly putty and roll it out into a snake and pull rapidly on it, it will snap like a solid piece. If you pull slowly it will stretch and elongate. I know lumber isn’t the same but it has some of the same properties IMO. Going at it slowly over time will allow the fibers a chance to adjust. Just as if 100 years ago that main beam was deflected 6 inches it would have broken but the steady push down over the years allowed it to sag. Windows and doors and everything in the building has moved and I would be looking at it all picking the point I felt enough is enough. And then stabilize the building against a proper footing. If the floors are still to sloped then you get into figuring out how to level them or how to live with them.

    Right now I’m working in my old garage that has some of these same issues and I want to support and stabilize the building but I’m only correcting it partway back for fear of really doing some damage.
     

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