Addition on back of house seems shaky

Hello All, I need some advice.
I have an addition on a 1920's house (addition built in the 50's or 60's I think). It is fairly small probably 6*6 or there about. It is supported by the house on one side and two cinder block pillars (it looks like). It appears that the pillars have sunk or something because the whole thing slopes downward toward the pillars. The pillars themselves I assume were built straight up now slope slightly inward and at a slight angle away from the house (would they have been built like this on purpose). Neither exhibits any movement or flex, but the floor of this thing is very bouncy. I would like to put a washer and dryer out here (the space is enclosed), but am afraid it may fall down or something. I was not able to find any rotting boards in the floor (it is exposed from the bottom).
If I were to jack it up using a jack (what weight is recommended) would it be acceptable to use 6*6 square pressure treated supports dug in and cemented into the ground? How do you join these as they will probably have to be longer than the eight feet I have seen at home depot? Also how much cement needs to be pour to stabilize them? Anyone know what the frost depth line is in Fred, VA.
Unfortunately I can't afford to pay out anymore money on the house as I already fixed a major sag, new kitchen and new bathrooms (and to boot had a miserable contractor who I am still fixing damage from).
Any help would be appreciated.
Thanks, Geoffrey
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stfuji wrote:

Sounds like incident in progress. Honest. Knockdown and redo, maybe. In compliance with code. Someone could really get hurt, from your description.

folks/officials should answer your questions. Can't see your place from here. :')
As emergency measure, you might put vertical timbers under center of horizontal framing, sitting on suitable (for soil/load) footings. Just so it doesn't fold in on itself, with you or yours in it.
J
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Personally I'd be thinking along the lines of digging holes pouring a little concrete with some re-bar and doing what the original builder should have done, build a footer. The above ground part could be done a number of ways, screw jacks like seen in basements would work & would give adjustment if it sagged a bit later on, you could build Hardy-board boxes around them for appearance's sake. or you could just round up a couple of Simplex jacks and raise it enough to put the blocks back with proper shims so it is level and plum. 6 X 6 isn't really much weight, travel trailers probably weigh as much.
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This may be a very serious situation. Not being able to see it, I surely cant say exactly what is needed. A few tips though. Footers should be at least 36". Your building inspector will know exactly. More is better if in doubt.
There are various types of jacks. Screw, bottle, etc. Before you do any jacking, look for some information on how to do it properly. You may need two or more jacks. They must be firmly situated on something solid to take the weight. You can only jack in small increments to avoid doing damage.
I'm not sure why you must join the 6 x 6's. Are you laying them horizontal as a sill support? With vertical support below them to the footers? Are the 6 x 6 replacing the existing pillars? How high are they? If more than 8', you don't join the supports, you buy the length you need to make them in one piece and cut them to size. They come up to 16' long. Using sonotubes, you can pour a pillar that starts 3' or more in the ground and extends up, thus needed shorter wood supports. I think I'd go 4' or more down.
If the floor is bouncy, there may be other problems, like weak and undersized joists. It may be smarter to tear this down and start over with a safe design.
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Thanks for the information all. Here is where I am at currently:
I did some more serious investigation last night. The pillars the provide the rear support are very solid. I.e. they don't move sway at all they have just sunk about a 1/4 to a half an inch over their life (which I can live with nothing in my house is straight. My concern is the akward angle. I'll post some picture on my site at some point this week to show.
I did discover the the floor joists are the actual culprit. The boards that make the perimeter of the floor are tripled 2*6 which look like pressure treated or newer board and are in very good shape. However there is an interior board which is older and lightly cracked nailed to these which provides the support for the floor joists which are also old and cracked. The whole interior is in danger of falling through if not re-inforced.
i.e. _________________________________________ || || || ----------------------------------- || || || || ------------------------------- || || || ||
where above each there are three outer boards from the house to the pillar and from pillar to pillar. These are very solid. Then nail inside these is a cruddy board with a notched joist resting on it.
I'm thinking at this point I'm going to empty everything out of the room (like sunday) and redo the innards using metal bracing off the solid three outer boards and redo all the joists before i find myself on the ground below.
Any better suggestions. I know its hard without some pictures. I try and post so people can see.
Thanks so much, Geoffrey Edwin Pawlowski wrote:

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Sounds like a pretty straightforward job. Sooner or later you are going to have to address the foundation however and that means some support resting on undisturbed soil below the frost line. stfuji wrote:

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