You need to get an assessment from a structural engineer.

You are really going to have a pro come and assess the situation and give you recommendations.

I live in a house built in the 1920s. Had a (maybe) 6' basement made out of a mix of brick, cinderblocks and clay. Water down there every time it rained. I hired a structural engineering company to design a plan to dig down far enough to give myself 8' finished ceilings for my home theater. I had 2 choices - underpinning so I could dig right up to the foundation walls (basically use the full footprint of the house) or come in from the walls as far as I wanted to dig down and leave a ledge all the way around the perimeter. I went with the second option because underpinning was like 5x as expensive. The ledge ended up working out just fine because I left all of my utilities against the walls and then built interior walls with closet doors/fake countertops to hide the ledge. Looks like the whole room has 8' ceilings - you can't tell. Anyway, this was a very very complex and costly project.

Hire a structural engineer. Do not attempt this yourself.

EDIT: Here's a pic of the "ledge" and how we had to get creative to dress it up. The drawers work and the doors open but the lower cabinets are mostly filled with concrete. There is about 8" of space on top of the ledge and under the drawer for storage but from looking at it you would never know.

And here is a pic of my equipment closet, which has the ledge inside but it's a regular door that goes to the floor.

Whatcha got there are some burial mounds in your basement and a sacrifice pit.

yea, basement walls and foundation walls are two different things. especially with cinder block. The dirt could very well be a factor in keeping that wall from bowing.

Without seeing pictures, they don't sound like they're structurally integral, but Geotechnical engineering is a dark art. Definitely get professional advice before excavating anything on the underside of your house.

This is the way. I do this day in day out with geo's and structural firms. Depending on what finding they arrive at will determine the scope. This could turn out be a very costly build. Without any information of your situation I could loosely suggest that you wall off the slab edge with a standard exterior envelope if you can justify the that the slab square footage will benefit what you're after.

Great solution to that problem, nice work

Thanks. I’m quite happy with how things turned out down there haha

I would guess (only a guess, worth less than you paid for it) that someone had to dig out the main drain to replace/fix it and just left the "spoils" there when done. If that is correct, then there is no harm in putting it back (if you are convinced the drain is working correctly, not leaking, etc.) Loose dirt is not going to be doing anything structural. And, of course, if the mounds of loose dirt don't touch the joists they also aren't doing anything.

The proper path forward is to get a structural engineer out for an inspection and consult.

And definitely keep an eye on that drain - are you sure it isn't leaking or easily obstructed so that the previous owner wanted it easy to get to?

Do you have my house?

Seriously though I'm in the same situation. I've just decided that the cost to do it right is not worth it so I left it alone.

My neighbor is a contractor and ended up digging out his basement to put in a two room apartment. Was really nice until it rained and he had 2" standing water. Renters moved out.

I wouldn't. If you take away too much dirt you could condemn the place.

Just leave it alone.

You absolutely cannot dig out that dirt on your own without some proper support. If you just try doing this on your own you might have the structure collapse on you.

A structural engineer can tell you if it can be done and specific methods for supporting the home during the dig out.

Some years ago a guy in my neighborhood decided to dig out his basement without consulting anyone at all. House started to fall in due to foundation failure, it was a shut show. Get an engineer.

That's super cool. The fake cabinets are a really fun, inventive touch that makes it look much better.

Mine was like this. Made extension to house. Dug out footings and left old dirt.

I have had my basement dug out below me in a two story house while living in it with my wife and young kids.

So it is totally doable.

Step one is to spend a couple grand on a structural engineer. They will go from your attic down to see whats up and make sure whatever is done is safe.

And a test for radon

You also probably want to get a radon test if there is a lot of exposed Earth in your enclosed basement

Licensed contractor here. Only saw "Digging out basement?" and "diy" and just wanted to stop by to say... No.

I have a crawlspace under my house instead of a basement. Is it theoretically possible to get it reengineered and dug out to a full height basement or is that just a recipe for collapsing the house?

Maybe.

I like those odds

If the dirt mounds are “just shy of reaching the floor joists,” then they are not “load bearing.”

yes, just make sure to watch some YouTube videos before you do

My house was built in 1922. I could not walk in the basement without constantly ducking my head (I'm 6'-3" tall). I was always hitting beams or HVAC ducts or bare light bulbs (always fun when you are bent over for some reason, stand up and take out a light bulb with your head).

I underpinned my entire house coming away with a basement that now has 8'-6" of headroom.

It's a long story and if you are interested, I can tell you how I did it later as I have to get my ass out of bed and head out just now.

But I will tell you this, the pay off is worth it but it is dangerous if you do it wrong. Think stages. Lots of stages.

How expensive per square foot was it to underpin and dig out if you don’t mind saying? Or maybe just how expensive was the initial structural engineer consultation?

They move houses all the time. You can absolutely lift the house, put a full basement, and set it back. The question is, is it worth the cost?

You bought that?

You can back pour cement walls using a “shutter box” and have a full basement. It will take some engineering and I would hire a contractor that specializes in doing such.

Hire a professional or protect yourself.

Underpinning is generally the best option for that. But connect with an experienced contractor in your area.

I am a licensed professional engineer (structural) in Toronto and I did my own design for both permitting and construction methodology. So it was free (figuratively speaking).

If I was to be asked to do a design for underpinning a basement my fee would be 10k to 15k which would include hiring a geotechnical engineer to do a borehole and give me a report on the soil I'm dealing with. Drawings would be signed and sealed, suitable for permitting and construction with all specs on the drawings.

As to the cost per square foot, I have no idea. I took a month off work and hired a foreman and two / three pairs of hands and paid them all by the hour. I also laboured / directed with the crew.

Work included new main sewer, new basement drains, some waterproofing, subdrains, excavation, new columns and footings, new concrete floor on 2 inches of SM, vapour barrier, crushed stone subfloor, new water service, plumbing work, and all new electrical panel and associated rewire.

100k to 125k (I didn't keep track of just the underpinning, it was part of a much larger renovation. I kept a spreadsheet of the entire project, which I'm still working on. So my price is an estimate.). Price does not include finishing the basement.

It's a lot of hand digging, staging, pumping of self compacting concrete, etc.

Thanks so much! That’s very helpful

This is a common project where I live in Baltimore. It usually costs at least 100k. Requires a structural engineer. If you have a local Facebook group for home improvement etc, you should ask around there.

As others have said, get an engineer to come and scope it out. I hired one to check out a foundation on a rental property. $550 bucks saved me 50k in foundation work.

If you are really dead set on doing this without help make sure you build temporary over engineered structural supports around your work site. Do small sections at a time. I honestly wouldnt do it without an engineer.

they took the bricks out to burry someone down there my man, that's just the extra dirt left

It can be done, basically lifting the house off the foundation, and rebuilding it(or just making the foundation taller).

On a smaller scale It’s been done to homes around me to get 1-2 more cinderblock layers in the basement to make it more habitable. I know of at least one case where somebody did this by themselves with a whole bunch of harbor freight bottle jacks.

I’ve also seen where an entirely new basement/foundation was installed adjacent to the home, the house moved on to the new foundation, and the old foundation then demolished.

Agree. This looks pretty much absolutely perfect.

I'm going to go out on a limb here and say the massive deep pit and the mounds of dirt almost touching the floor joists are related to each other.