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Heave Ho When all the jacks are in position with solid cribbing beneath, we first extend them until they are fully loaded — to the point where the cribbing stops pushing down into the soil. At this point, lifting can begin. I prefer to work down the long side of the house — the eaves side of a typical gable house, for example. By sighting down the long sills and the center girder, I get a good idea of how the house is behaving as it is lifted. It’s ideal to have three guys jacking and one guy going for material as they need it. The three guys position themselves across the front of the house (if that’s where we’re starting from), one at each corner and one in the middle. They’ll each raise their jack just enough to accommodate a 1/2-inch plywood shim under the adjoining pier. Then they’ll move down 6 or 8 feet to the next jacking point and raise that jack 1/2 inch, and so on down the length of the house. A restrained approach like this eliminates a lot of consequential damage to interior plaster, doors, and windows. We repeat the process until the fourth pass, when we pull out the plywood shims and insert a 2-inch concrete pad. Then the process begins again, adding plywood shims on top of the concrete pad until the seventh or eighth pass, when we insert a 4-inch concrete pad. We continue the process again, inserting an 8-inch pad, and so on, until the house is raised a few inches above the new specified grade, which might be anywhere from several inches to 4 feet, depending on the owner’s wishes. Occasionally an owner will ask me to lift the house just high enough to replace the rotted sills then set it back down only 3 or 4 inches higher than it was previously. That’s okay if just one side or section of a house needs work. But if I’m going to overhaul the entire foundation, I prefer to lift the house at least 2 or 3 feet so I have room to work. Usually, once the house is raised up, I leave it up permanently. It saves me a lot of work, since I don’t have to take the house back down, and the plumbers and electricians like it a lot better than swimming in the mud. It’s also in the owner’s best interest, since there will be fewer termite and moisture problems, as well as easier access. If the house gets set back down close to the ground, it’s only a matter of time before the work has to be done again.

New Piers

Once we get the house jacked to where we want it, we pull string lines to lay out the new masonry piers. The piers are built plumb and square from either block or brick and allowed to cure. Then the house is lowered, in a reverse procedure. Occasionally, if the client requests, we’ll excavate down a few feet and put in a half-cellar wall. We build them out of block; they’re called chain walls in this area. I leave a ventilation hole by laying every fourth block in the top course on its side. In our damp climate, though, I prefer to leave the house up on pilasters and completely open underneath for good cross-ventilation. While the house is raised up, I usually spread about a foot of bank sand underneath to avoid standing water and mosquito problems. I also slope the grade away around the outside.

Using Pipe Staging for Jacking

On a recent job we were able to use our pipe staging as a jacking platform. It was a carriage house with an apartment above, built around 1900 (Figure 3).

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Figure 3. This turn-of-the-century carriage house was 19 inches out of level and 12 inches out of plumb before renovation. Termites had made mincemeat of much of its wall framing.

It had been built on 6x6 sills right on top of unstable soil. A previous owner had placed reinforced concrete, 24 inches thick in some places, on the floor and under the sills to try to stabilize the structure, but to no avail. Termites were eating their way up through the first-story framing to the second story. When we got there, the building was 19 inches out of level and 12 inches out of plumb. We had to support the second-story apartment while we repaired and replaced the first-story walls. I used my pipe staging as a convenient jacking platform, setting it up two bays wide and three rows deep (Figure 4).

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Figure 4. Staging made a convenient platform for jacking the carriage house (top), but it had to be thoroughly braced all the way to the ground. In addition to continuous cross-bracing in both directions, the author set 6x6 posts under the critical jacking points (middle), and made stable bases for the scaffold legs (bottom) by drilling holes in 2x6s.

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Before using the staging for jacking, I called a local scaffolding distributor to find out how much weight it could carry. But rather than rely on the staging to carry the loads, I used 6x6 posts all the way to the existing slab under each jack. I put 2x4 cross-bracing along the top of the staging, connecting all three rows together from the front to the back of the garage. I also stabilized the bottom by making bases out of 2x6s, with holes drilled for the feet. I then connected these bases and the bottoms of the 6x6 posts with double 2x4 braces running across the width of the garage.