Un-nailed mortised floor joists about to drop?
I have a circa 1900 house built on 8”x 8” rim joists, and one of these has bowed outwards. The 2”x8” notched joists were never nailed into the mortises, and those nearest the “apex” of the bowed section appear to be bearing on perhaps just 1/8”-1/4” of the notched end, and are at risk for dropping into the basement below. There is no sill plate, just the 8″x8″ rim band with mortised notches, which carries the 2”x8” floor joists. I need advice on what a good (and low cost?) solution to the problem would be.
Should I simply assume that the rim joist is permanently bowed and go about sistering joists at the “new” length(s)? How would I go about securing the ends to the rim joists? (Using joist hangers is difficult since the original 2x8s are closer to 2″ than 1 1/2″, and are also just 1/16″ above the stone foundation wall which extends into the basement..) Or, should I attempt to pull the rim joist back to its former configuration, and if so what is the best method for this? (I’ve considered threaded steel rods or steel cable with a come-along, but haven’t found a resource describing either technique.)
For the moment, to prevent the joists from dropping, I’ve installed a short carrying beam in the basement under the affected joists, supported by a pair of posts. To prevent (or at least retard) further outward creep of I’ve also installed two lengths of aircraft cable running between pairs of large eye screws with turnbuckles at the centers, and have tightened as hard as I could.
The bowed end is at the “front” of the house, under one of the roof peaks rather than one of the side walls. The house is pretty small: the overall dimension of the affected floor area is about 11’x12’. The 2-8 joists are about 11’ long and run between the rim joist and an 8”x8” carrying beam spanning the middle of the house. The joists are pulled out of the mortised notches there as well, but to a much lesser degree.
The rim joists (and the mortised ends of the joists) are quite difficult to access from the basement. This is a “Michigan basement”: the rim joists are supported by a stone-and-rubble foundation wall which is about 16”-18” thick and 18” tall, which in turn sits atop a sloped wall of dirt parged with concrete. At the affected end, the stone-and-rubble wall appears to have been moving outwards with the rim joist, to the degree that there is a 2″ gap at one of the inside corners. This is not visible outside probably only because it has been patched at some point. I’ve already stabilized some water issues at the exterior, and will need to also undertake some foundation repair. However, what I do depends on whether the rim joist gets pulled back into position or not.