Digging around basement poles - HELP!

I have a basement with a dirt floor and an average 7.5 foot height to the floor joists above. I want to take out a foot of dirt and have a concrete floor poured so that I can finish the basement in the future. Of course the poles in the basement will need to be replaced because the footers for them are not deep enough to support lowering the floor a foot. My contractor says I can get the dirt out myself to save a ton of money in labor and all I need to do is give a two foot boundary around the base of the poles to keep them in place until he comes in and replaces the poles and pours the floor.

-----Does this sound right?-----

I have read that it is possible to dig around a footer (of the pole) as long as you leave a 45 degree angle of wider and wider dirt as you go lower. The footers of the poured walls are down farther than I need to dig so I am not too concerned about them.

Since I can save about $10,000 in cost to dig out the 1300 square foot area and use the dirt in the yard it seems like a good plan. Is it a safe idea?

 

In underpinning foundation footings it is proper to leave a 45* angle away from the footing or pad. So go ahead and excavate around the pads leaving the required slope. For that extra ounce of prevention, if there is going to be an excessive time lapse from excavation to the arrival of the contractor you could build a crib around the two foot boundary braced with re-bar or wood wedges driven into the dirt

 

The recommendation assumes a well blended sandy material. A high water table, loose sands, cobbles or gravelly material, and clays may not work. Make sure the contractor is sure about the soil conditions. You may want to hire a foundations engineer, since the contractor will not be liable for your work regardless of his recommendation.

Make sure you lower dirt for your desired clearance plus: a 6-8" stone subbase, vapor barrier, 2 inches of sand, a 4" minimum concrete slab, and finished flooring.

My brother-in-law excavated a deep crawl space by bucket loads to create a room in his last place. It's hard work, so eat your Wheaties! Good Luck!

 

It's not cobble or gravelly and the contractor has looked at it. It might be clay only because I'm in Georgia and the dirt is kind of reddish. My experience with identifying clay comes from how it is when it is wet, since I've never seen this wet I'm not so sure.

But - it would take more than Wheaties for me to dig that out, I'm going to rent the smallest of Bobcats or a Dingo for this one.

The contractor says I can put up as many 4x4 posts as I want in the meantime (in addition to the original poles) while I dig and wait for him but I guess I'll have to ask him how low to dig. Luckily all of the poles are on one beam that runs the length of the house.

I know he is using gravel and such and he is concerned about keeping water out even though there hasn't been any since the house was built in 1991. What should I make sure he uses for a vapor barrier? My termite company wants to treat down there before concrete is poured so I have to coordinate that too.

 

I am pursuing a similar project (lowering the floor by the bucketful). I am currently digging a trench near the outside foundation walls for the lateral sewer line. Is there any chance that I could destabilize the foundation wall (block/brick/mortar) by removing the current 2 inch cement slab and underlaying dirt next to the wall?

 

How far down do you plan to dig?

Are you replacing a concrete slab currently in place and does it have a similar sewer line already in place or is this a new feature?

I need to find the answer to this question myself even though I don't plan to dig below the footings on the wall I would like to know where I should stop. The bottom of the footing is a little over a foot away from where the surface of the dirt is now. This would ba about 9.5 feet below the top of the floor joists.