My house is a raised ranch, rectangular in shape measuring 24' wide by 44' long. The basement walls are concrete block about 5' tall. On top of the concrete block is a pony wall (short wall) about 2'-6" tall. On top of this is a platform framed 2"x10" floor system. Down the center of the basement is a steel I-beam with steel columns.
My issue is that the pony wall is bowing out at the top about 3/8". This is occuring on both side walls in the middle 20' of wall.
I first noticed this when I was replacing the rotted plywood floor in the bathroom. I noticed a gap between the floor joist and the rim joist. My first thought, since the house is 50 years old, is the joists dried and shrunk a little. After inspecting other areas, I suspected bowing and used my 2' level to check. Sure enough, at the corners the pony walls are plumb with no gap between the end of the joists and the rim joist. As I worked my way to the center of the side walls, the gap increased and the walls became more out of plumb.
The walls are only 3/8" off. But since I"m residing and doing all kinds of work, I might as well straighten this out. I plan to use a turn buckle with cable or chain and some eye bolts with big washers and some scrap lumber.
My plan is to drill a hole through the rim joist on each wall for placing the eye bolt through and then have a piece of 4x4 or 2x6 lumber on the outside of the house that the eye bolt also goes through. I'll use a big flat washer and nut. Then inside I'll attach chain or cable to both eye bolts with a turn buckle in between.
My plan is to use about 3 or 4 these along the length of the house and then to ease the walls toward each other over a period of time.
My question is this: how much weight should the turn buckle, etc. be rated for? Which is better chain or cable? Any suggestions?