So where were we? Ah, yes. The concrete has been removed and the holes have been dug. The most remarkable part is just beginning. For the most part they have tried to place the piers under the foundation beams as that will affect more of the foundation with fewer piers.
When the holes are dug, they have dig out to the side as well as down so they have a place to drive the piers. The way the holes are dug there is a place for the worker to sit while they drive the piers. Take note - when they are sitting in the holes, the tops of their heads are at about floor level. Those are deep holes!!!
To drive the piers they use an electric kind of jack that appears to use the weight of the foundation above to help move the piers down thru the dirt to bedrock. They use round concrete piers that are about a foot high and maybe 8" in diameter. (These are my estimates from observation and not from actually measuring. ) As I remember it took about 16 of these to reach bedrock!! This is not a quick process, but it a bit less labor intensive than the digging. These cylinders also have a small hold in the center into which rebar is inserted for extra strength.
Once the piers are all driven the the real fun begins. They bring a hand-operated jack into each hole and the foundation is jacked up all at the same time. They do a few pumps of the jack, measure, more pumps, until the foundation is level. The change is so subtle, but so dramatic. Example - my computer armoire fits into a corner that is in the approximate middle of the house. For a while now I had to keep a hold on the sliding keyboard drawer while typing to keep it from rolling back into the unit. I was working on the computer while they were doing the leveling and it suddenly occured to me that the drawer wasn't rolling back any more.
After everything is confirmed level, they they put a rectangular block of concrete on top and then two smaller cylinders on top of that. Then they have to start filling in the holes. That means bringing all the dirt back in. After filling the holes they water in the dirt to be sure it's well packed. Then they pour concrete patches over the dirt and all is pretty well finished. To make sure there were no kitty prints or Barbara prints in the concrete, they placed the same boards over them that they had used to cover the holes overnight. The did boost them up with some of the metal shims they use to let air come in to hasten the curing. (They used the excess dirt to fill in around the foundation where the shrinkage had opened voids.)
I also had to have one new pier outside, just past the front door and the process is the same except for the concrete patches. The crew was nice enough to put some concrete around a fence post that had been loosened by the digging. Believe me, that post won't be going anywhere for a long, long time!!!
At the beginning they had planned to shim up some existing piers located under the wall between the garage and the house, but they also ended up having to shim up two more on one outside wall of the garage.
I have to commend this crew from Atlas Foundations for their professionalism and courtesy. The tolerated my curiosity about the process and answered all my questions to my satisfaction. I would have them work in my house again in a minute!
This is just the dirt from the bedroom and hall!
The dirt from the kitchen was out in the driveway.
Driving the piers outside.
Driving the piers inside (in the kitchen).
See how deep this hole is?
Can you see the space between the slab and the top of the dirt?
It's about 4"!
Finally, the work is done!
Tomorrow I'll post the "after" pics. Really amazing stuff!!