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Setting Up We start by distributing jacks around the perimeter of the house at intervals determined by the size of the structure. There are no real rules of thumb; you just have to properly estimate the weight of the building and place jacks accordingly. Obviously, a two-story structure will have jacks at tighter intervals than a single story. The corners usually hold themselves up pretty well, providing the framing is sound; most of the weight is in the middle of the building. We usually place jacks alongside existing piers, if there are any, since these are already supporting the structure and provide a place for shims and blocking as the house goes up. As we distribute jacks, we scope out the areas where we’ll have to excavate. Since the jacks must bear directly underneath the sills, we usually have to do a fair amount of digging to accommodate both the jacks and the cribbing they rest on. We take care not to position jacks or cribbing over any septic lines, gas pipes, water supplies, and so forth. When we’re working on an unoccupied house, it’s an easy matter to disconnect the plumbing and electrical before the job starts. If the house is occupied, we provide temporary wiring and plumbing to ensure uninterrupted service to the home while we work. We’ve learned by experience to watch out for live electrical wires lying in the dirt. While setting out the jacks, we also look for rotted sills and joists — places where we’ll have to scab on new framing or install "needle beams" (Figure 2).

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Figure 2. After decades of settling into the ground, this house (top) is showing serious moisture damage. New floor joists (middle) provide a sound structure for jacking. The framing nailed to the wall helps to pick up individual studs and the corner post. Note the new elevation of the porch rail relative to the concrete porch (bottom) as the house comes up.

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Needle beams are temporary wood beams set in from the edge of the house underneath and perpendicular to the joists. The needle beams stay in place for the duration of the job and are used for jacking until the house is high enough so that the sills can be replaced.