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Jacking Floor Joists???


Handyman663's Avatar
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12-19-09, 12:29 PM   #1  
Jacking Floor Joists???

I have a 1902, 25' x 40' house that has about 1-1/2" of sag in the center. A second story was added in 1975. I would like to level this, but would not start jacking without some good advice. Obviously, it would cause plaster cracking on the original first floor and drywall on the 2nd. That is all cosmetic and I could repair, but I get antsy thinking about plumbing and furnace vents on the roof. The foundation is stacked field stone with a little mortar.

Anyone out there ever try anything this nuts????

 
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12-19-09, 03:43 PM   #2  
Hi handyman. Stabilized a few, but never really lifted them much. With the second floor addition added 73 years after the house was built, I think you are going to have a problem lifting it. Essentially, while lifting the lower older structure 1 1/2" to get it back to level, you will be forcing the newer structure above to be 1 1/2 inches out of level. May not be that entire amount, but some portion of it. And it will fight you. There is an older thread here on the forum where they jacked the middle of the house and lifted an outside wall right off the foundation, and it wouldn't come down.

My thoughts would be to put some pressure on it and see what happens. Pipes that are anchored to the house will move with the house. Pipes and/or the chimney that are anchored to the ground will not. You can't rely on the screw jacks they sell at the big box, they are not designed to lift those weights. And you can't trust the beams currently holding up the house, they were installed when the weight was distributed across many points. Like arthritis setting in, the house has become rigid and you have the potential that just a couple of points will be carrying the bulk of the weight, especially since you will not be able to measure that pressure. And if one fails, that load will shift somewhere, risking a cascade of events. I'm not an engineer in this field, but from my construction/contracting I have deep respect for the loads above.

Let's see what the pros have to say.
Bud

 
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12-19-09, 04:20 PM   #3  
Thanks Bud

I knew there were a lot of things I hadn't considered, but the second story didn't enter my small brain. In the daylight of tomorrow I'll check the 2nd story for level. I had always wondered if the weight of the top floor had exacerbated the deflection of the old structure.

The things really bugging me on the bottom floor are my refrigerator that I have to shim 3/4" to get into the range of adjustment on the casters and the original front door that has at least 1/2" of slope across it.

Maybe I am nuts. I would hate to lift a corner of the house that would not return.

 
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12-19-09, 04:40 PM   #4  
Found the thread if you are interested: http://forum.doityourself.com/bricks...ont-level.html

How much interior work will you be doing, doors, windows, drywall, floors and such? The more you remove, the more things will release.

Bud

 
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12-19-09, 07:27 PM   #5  
With the addition in '75, you may have trusses. Check under them for the needed lift space. You probable have it if the wall studs were all mill cut the same..... That ceiling/wall joint will need adjusting (cutting some of the wall top's drywall) before you start because the wall is holding up the ceiling there.
The flues going through the roof may need attention also.

Be safe, Gary

 
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12-20-09, 07:30 AM   #6  
Quick Education

This is a great board. I have learned in less than a day that I would be in way over my head as a DIYer. Bud's comments made me realize that for openers I would probably need a steel I-beam to run the 40' length to augment the old 6 x 10 fir. Secondly, those photos in the old thread frightened me out of my skin. That project cost more than my net worth. Maybe I'll just tolerate the leaning refrigerator and front door that has been shaved into a parallelogram over the last century. For whatever it is worth the 2nd story does not have trusses, but is rafter on beam, with no attic space. Thanks to all.

 
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12-20-09, 07:47 AM   #7  
What you might consider is placing some extra supports in the basement to stabilize what you have. That way , in another ten years it will not be another half inch down. My home is way younger than yours, but I installed posts right next to the existing columns. Ever year or so I get ambitious and put some pressure on them and hammer the shims in a bit on the original supports. I've made a little progress by letting the house move as it wants, but basically I've stopped the cracks and sagging floor.

Happy holiday
Bud

 
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12-20-09, 10:14 AM   #8  
Point well taken on preserving what I have. I did check the 2nd floor today and while there is some sag, it is only down 1/2-5/8 thru the center. If I were to jack it, splitting the difference might be a good compromise. That would put the first floor with about 1/2" of sag and the second floor with 1/2" of hump.

I am supposing that the framer in 1975 leveled the second floor joists, meaning that the house is sagged about 1/2" in the past 35 or so years. He did build it "hell for stout" by placing 2 x 12's next to the old ceiling joists.

I have learned a lot and the detective work is fascinating.

 
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10-17-12, 10:09 AM   #9  
Yeah, I know, old thread

Yes, I know this is an old thread, but what I have to add is very relevant.

My parents had similar issues with the house I grew up in (now, how do I NOT end that sentence with a preposition?)

Our house had been on a stone foundation, and was eventually moved by crane onto a concrete foundation (two dump trucks used as counterweight and they still lifted off the ground). Two support beams were added under the structure with jack posts at each end and center.

The house was also old like in the original post and had also had a second floor added during its life. The first floor also sagged over the years. Rather than try to jack up the first floor, thereby encountering the problems mentioned in the thread, here is what we did (I helped as a 12 or 13 year-old, yay for me).

We took a length of straight-edge and layed it across the floor with one end at the foundation and the other end just within the interior wall space. We placed a level atop the straight-edge and leveled the straight-edge. We then measured from the bottom of the straight-edge to the floor every six inches or so along the width of the room. We then moved down the room 12 or 16 inches and did the same exercise, and did this for the full length of the house.

We then took 2x4's and transferred the measurements onto the 2x4's and ripped them. The ripped 2x's were then secured on edge every 12 or 16 inches with the cut edge down, and a new subfloor was attached to the leveled 2x's. The support beams already added below kept the old floors from sagging any further than they already had. This new floor was level (or reasonably so), quiet, stable, and still in use today (by a new owner).

 
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10-17-12, 12:01 PM   #10  
" The house where I grew up had similar issues ?"

But don't worry the grammar police aren't too strict here.

 
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10-17-12, 01:37 PM   #11  
Furd is always lurking, so be careful.

So rather than fixing the hurt, you bandaged it. Sometimes it works well. Lifting houses of age is always a problem and requires diligent research. Glad you got yours going.

 
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