There's a 4' x 3' x 1.5' poured concrete block at the bottom of the
back steps that's shifted down and to the left about 2 inches.
I've dug a 12" wide and 12" deep "tunnel" under the block's low end
and can get a small 2-ton bottle jack under the block. With 2x6's
above and below the jack, I can raise the block the required 2 inches
to level it.
Now I need some ideas/guidance on how to permanently support and hold
the raised block in place. I would like to pour cement under the
block, but I don't know how to temporarily hold the block in place as I
removed the jack so I can pour the cement under the block.
TIA for any tips, suggestions, ideas.
Use bricks and plastic shims. You will have to install the
bricks and shims, set the weight down on them and see if it
sinks (it will probably sink a little). Jack it back up and
add more shims or bricks. Repeat as necessary until steps are
where you want them, then pour the concrete. Be careful not
to bump the brick column when working the concrete.
I assume this block is a landing at the base of some steps?
If you're going to have to place some more concrete to stabilize the
block...perhaps an easier approach is to remove & replace the block.
It's pretty thick.....frost zone? Because structurally there's no need
for something that thick.
Your block is about 2700 pounds so be careful when working around it
Is the soil under it sound? No organics?
I would also suggest just adding leveled smoothed sand under the block.
The block is so heavy you'll need to get good uniform bearing against
the soil so that it doesn't sink more. Local shims & blocks, unless
over a large area will also sink over time, hence the need for more
Why did the block sink? With uniform bearing that's less than 250
pounds per square foot...way less than even crappy soil can handle.
The block of cement is the footing for the back porch stairs. We live
in Massachusetts where we can sometimes go well below zero F degrees
which will create frost heaves.
I really don't know why the block sank 2 inches. But after digging the
12"x12" tunnel under the dropped end to place the jack, I think it is
all the sand with little to no rock in the mix.
I really don't have a lot of room to work with under the footing, so I
placed a rather large cement block in the tunnel and jacked up the
footing enough to get one course of cement bricks on top of the large
block. I then let the footing rest back down on the bricks. The brick
support structure has sunk a bit into the sand. I will jack up the
footing tomorrow and place another course of brick in place on top of
the others and see how high that holds the footing. If I'm just a
little over and the next morning I'm at level or still a little above,
I'm going to pour cement to fill the entire hole and surround the
bricks. I'm hoping this is enough to hold the footing in place for a
long time. If I get more sinking, I will dig from the other side of
the footing and jack it up and pour another cement support.
Thanks again to everyone who has posted to this thread. Many good
approaches and ideas that made it hard to choose the one I could work
with the best since I'm not a construction guy
Im sure what you are calling a "block" is the footing for the
steps..This is a very common problem. The easy way is to leave the
jack in place and form up all of the area you can around it and pour
the concrete. After this remove the jack and fill in the void. Its alot
eaiser than it appears. This is the same way we do house foundtions
that are under a recently moved houses, we "block out" around the beams
and after the house is set down then go back and fill them in. Good
luck..BTW if the steps are concrete I would wait about a week or so
before letting the jack down.
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