Digging Footings-obstructions

Greg Di

What do you all do when you are digging footings (for a deck or porch) and you hit immovable rocks, old footings that buried, buried concrete, etc...

The last deck had 10 footings and it took 4 guys 9 hours to dig them due to rocks and other BS. Half the footings had to be cheated a few inches left or right just to get the tube in. Then we hit a decomissioned septic tank which required jackhammering through the lid enough to get a bigfoot in.

I have not had an easy dig on the past couple of decks I've done and the one we started today had 4 of 12 footings "go bad" in terms of hitting underground objects that would prove very difficult to remove.

The footings have to go where they have to go. Are you able to put your tubes on top of objects that are solid and pour onto that even if it doesn't meet the min. footing depth?

I'm curious what others do because I can't see ripping out someone's entire backyard for the sake of a 12" footing. What/how do your inspectors handle it? Digging holes should not be this hard.

Bone Saw

Greg I can definitely tell you a thing or two bout drilling footings. What I don't know is what kind of rock you're hitting. North Jersey is pretty rocky, like pa, I get alot of shale (lol) and smaller quarts and pa field stone (a bitch). I think I have it down to a pretty good system.
A jackhammer completely lacks the finness and is heavy and cumbersome when down in a hole. I had 2 18" hex/spline chisles joined to make a 36" chilsle for my hitachi spline rotary hammer. I also have a hilti demo hammer with a 20" bit I had made by taking a digging bar to a machine shop and had the shank milled to fit the hilti. this works like a dream. You can definitely tell by the sound and vibration through your hands and through your feet weather you have something watermellon size or refridgerator size. When I get a rock that has the skidder jumping around and the hammers just dance around with that "ping" noise and not a hollow "thud" noise, I put about 4-5 holes in it drive in simpson titan screws leaving about half exposed and pour, Inspectors have never a problem with this. The hydraulic auger I have on my mini skid I have a pengo style teeth on it I will usually break right through most football size and smaller rocks unless the point is right on the rock. when I hit something a little bigger a little work with the hammers and the auger will usually just finnish the job. low speed high tourqe is the key

K2

When I did foundations in NJ in the 70's we just used the giant rock/boulders as part of the foundations. We'd butt, cut, chop, go over, whatever it took. I'm sure those houses never moved.

I would take that for bedrock any day over the crappy soils we have in the flatlands of CO. I've drilled 40 ft to what the engineers called bedrock which was just a little better crappy clay than the first 40 ft of crappy clay.

RobertCDF

I use a jackhammer with a clay spade for most of my holes... But if I hit a large rock that fills the entire footing and then some. We are allowed to drill into the rock and set rebar and pour as normal. Although since I bought the jackhammer I have only had to do that once.

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Robert Shaw
Colorado Springs Custom Decks
Colorado Custom Decks
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joasis

And there is always dynamite!.. ..You know, I am 45, and when iwas a kid, the hardware stoor in town still sold such things as dynamite, red phosphorus, and such...probably at the discretion of the store owner who decided the use or threat level. Farmers used dynamite to clear trees and pond dams...etc...times have changed.

So when you busted through the septic tank lid and placed a "bigfoot", I assume the tank was dry???

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Greg Di

Yep, it was filled to about a foot below the lid with gravel. that's what I put the BF on.

dkillianjr

Now this might be a dumb question, but whats a bigfoot?

Dave

Bone Saw

http://www.bigfootsystems.com/AbsPag...iteid=1&lang=1

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dkillianjr

O ok thanks, Ive always call those sono tubes. You learn something new everyday.

Dave

Bone Saw

me too Its the plastic form @ the end of the tube

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Chester County Custom Decks
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Standstrong

I write in my deck contracts:

-All footings to be at least 10'' in diameter
-All footings to be at least 42'' in depth
-Any and all obstructions to be paid at a rate of $75 per hour until removed.

It wont stop the blood-flow, but it helps the loss when you've got 3 guys with pinch bars sparking away the granite watermellon.

I write down exactly when we hit something and exactly when we remove it.

Greg Di

The sonotube is the cardboard part. I don't use bigfoots unless I have to because you need to dig HUGE holes to get them in. It's easy enough to dig a trench with a backhoe, but most times, I can't get a machine into the yard to did a trench.