Jack & shim foundation repair steps - feedback appreciated!

vacatari

Concrete has settled in one corner of a single floor 1000sf house house due to poor drainage. It's low in the corner about 1" at its worst.

Can someone tell me if this sounds like a reasonable approach to fix....

- Unbolt the foundation bolts along the two sides of house making up sagging corner

- Get 4 concrete pillars with the wood top base
- Get 4 heavy duty (12+ ton) bottle jacks
- Get a very long 4x4 or 4x6 to span as much of the house as possible (16' minimum... length of house better). For this lets say 4x4x16'

- Distribute pillars evenly for length of 4x4
- Put bottle jacks on top of pillars
- put the 4x4x16' on top of bottle jacks
- use long drywall screws to screw 4x4 into floor joists, to hold 4x4 in place while jacking

- Jack house until level
- Use simpson strong tie metal shims to shim the low spots. Stack/weld together where more than a couple are needed
- Use high PSI concrete (5000psi ok? more?) to fill the remaining gaps near the shims

Not sure about order of these steps:

- let concrete dry
- screw foundation bolts back down
- remove jacks
- remove 4x4x16'

Any feedback? Is there any building code covering foundation jack/shim repair like this?

Bondo

Ayuh,... Your gonna need Lag Bolts, not drywall screws...

vacatari

It's a temporary beam.... I was thinking not to damage the joists too much

jlhaslip

Be careful jacking on the joists. You will need to shim/jack the rim joist as you proceed in order to avoid messing up the joist connection. They are likely just nailed.
Also, use dry-pack grout instead of concrete.

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vacatari

Would you shim with PT wood? or metal shims? The only thing I can find today that would get me to the approximately 1" shim (at worst) is probably going to be Simpson strong ties stacked up (can weld them together too) or PT wood from Home Depot.

What type of dry-pack grout? Why this vs concrete?

Thanks!

Bondo

Ayuh,... You're still lifting the weight of the house, in a shearing motion....
I'd use Bolts...
You're only shimming an inch or less... Grout is strong with No stones in it...
The stones could be taller than the total shim...

vacatari

I've read only to lift 1/8" per day.... we've got drywall off, windows will be replaced, and stucco will be refinished. Do I need to consider the 1/8" day rule here? Or can I just (slowly, listening to the house) jack it to level?

jlhaslip

Keep your ears and eyes wide open and go for it.
Take it an eighth above level, shim it, pack it and lower it down after the grout is dry.

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Daniel Holzman

Just out of curiosity, have you fixed the drainage problem that you believe caused the concrete to settle? If not, what is it that you believe will stop the house from settling some more after your repair is complete?

vacatari

Got a quote to move some dirt around and grade it. We're doing the draining.

$4000 for a day of bobcat work... is this reasonable? First quote...

jlhaslip

$400 sounds more reasonable for a day's work with a Bobcat.

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Aggie67

Non shrink grout is the way to go. Read the package, though. Most manufacturers recommend extending the grout with pea gravel when the grout is going to be over a certain thickness. (The pea gravel acts as a heat sink.) Mix it up dry, like the consistency of beach sand near the water line, the stuff you can readily make a sand castle out of.

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jomama45

You're going to want to put a 1/4" steel plate between the post & and jack also. As long as the house doesn't have a masonry veneer, your plan sounds good to me.

vacatari

Great!

Yes - using a 10' x 10' x 1/4" aluminum (?!?) plate under the beam then a piece of 1.5" x 16" x 1/4" STEEL bar meeting up with the aluminum to spread out the load and not punch through the wood with the bottle jack head. Something ike this...

[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[ Joist [[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[
[ ] 4x6 beam
-------------------------- Aluminum plate
---- Steel bar running down the beam about 16"
ooo Bottle jack head


Here's the update:

- Only wound up going with (2) 20ton bottle jacks on each side of a 12' 4x6 beam
- Cut out a section of the floorboard on each side to work & dig
- Dug out the spots for the concrete piers
- removed foundation bolts along the two sides making up the sagging corner

Ready to jack and shim today

Home depot has some 1.5" square plates (with a hole in the middle) in the Simpson strong tie section that we're using for shims. Also flat steel from the rebar section

vacatari

It's shimmed & level. Grout tomorrow.

The lowest points took a stack of 6 of the simpson strong tie square washers that are about 2" square and 1/4" thick (That makes it 1.5" out.. ouch. We stacked them together and welded the stacks of 6, 5, 4, 3, 2, then tapped the shim stacks snugly in place with a flat iron stake from the rebar section. For those reading -- it would probably have been a lot cheaper to go to a nearby machine shop during business hours and buying a bunch of flat scrap metal.

I'll post some pictures at some point.