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Can load bearing walls shink/compress?


Jaz-man's Avatar
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Join Date: Oct 2007
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10-07-07, 12:00 PM   #1  
Can load bearing walls shink/compress?

I could sure use some help with this puzzle:

My house is 28 years old with with a noticeable sag in the center (where there is a turning staircase) on the second floor. You can notice the sag from my kid's rooms (2nd floor), which is pretty disheartening for a '79 vintage house. I'm measuring from the outside wall to the inside walls defining the staircase/hallway area. It's about a 12' span.

Starting in the basement: The wood beams seem pretty level (within 1/4 inch across a 30' span) The poured foundation has some cracks but doesn't show any signs of movement. But, the top (where the sill sits) is level, but has some areas that wander about 1/2" from true flat.

1st floor: Slopes toward the center of the house about an inch in the worst area.

2nd floor, however, is sagging everwhere from as little as an inch to as much as two inches over the same spans.

Have my 1st floor load bearing walls buckled/bowed or some other way shrunk an inch or so?

I don't know if this is related, but several of the door casings on the 2nd floor have been pushed off the door frame by drywall that seems to be buckling. (You can see a 1/2 inch gap between the door frame and casing where the drywall has pushed the casing away from the frame.) I don't notice this problem on the first floor doors.

I have an idea how to jack the 1st floor from the basement (should I choose to), but how do you jack the LB walls on the 1st floor to level the 2nd?

 
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Concretemasonry's Avatar
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10-07-07, 12:17 PM   #2  
Can load bearing walls shink/compress?

All walls and columns under load get shorter over time. This is called "creep" and wood does it more than other construction materials.

Also, the wood has shrink from the time the home was built (drying out).

Because you are looking at the second floor, you are getting the combined effects from the basement posts, first floor joists, the first floor walls and anything else up to where you are seeing the distortion. - This is common with wood construction.

If you do not have any movement in the foundation walls, the 1/2" variation should not be a factor since the home was built plumb, level and square on top of this variation.

You could have some settlement of the footings under the basement posts or you just have more shrinkage than you want for the doors to work correctly. The first floor can be jacked up to provide some correction to the second floor. - It must be done slowly and is really not a DIY project unless you are willing to live with any problems created because of a lack of experience.

Dick

 
Jack the Contractor's Avatar
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10-07-07, 08:04 PM   #3  
Before you do anything, you should have a structural engineer or a building inspector look at it. I have an idea what is happening, but I don't want to send you off in the wrong direction. This is not a DIY project. I have done many of these and they are never good. Get a professional opinion. Good Luck

 
twelvepole's Avatar
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10-07-07, 08:09 PM   #4  
When it comes to load bearing wall issues, it is always best to call in a structural engineer. This will be important at time of sale and disclosure statements. You will want to do what is best for your structure.

 
Jaz-man's Avatar
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10-08-07, 02:43 PM   #5  
Thanks

Thanks for all your help; you pretty much confirmed my suspicions. I'll let you know how it turns out.


Thanks again,

J-m

 
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