Ground Level Basement Problem

It might help if you found a picture of a house/barn that had what you are looking to recreate. People may know of the proper cheats or methods to use if they could be a better mental picture of what you want.

That and it will help avoid them having a different mental picture of what you want.

Have you thought of experimenting (on a different lot) with the raise terrain cheats?

http://simswiki.info/wiki.php?title=Tutorials:Basement_Tutorials

Know only the standard terrain tools, and the stairs method of excavating I found about from you. That works just fine. What I need is to be able to do a vertical cut so the lower wall lines up flush. That or a way to get a ramp to the barn door. Am currently using a blank lot provided solely for experiments.

Perhaps, but I have no way of posting pictures. Objective: rectangular barn on ground level, ground at rear of barn slopes downward so there needs to be structure (basement, at least partial) directly under barn walls. Tool needed: straight vertical cut at perimeter of excavation, not the ~85 degree slope that now exists.

You could post an image from Google images. Those are already hosted somewhere.

Or a link to a page that has an image of what you're looking for (letting us know which image if there are more than one on the page).

I finally found SnootySim cheat lists again, (thankyou @Rflong) I couldn't remember the cheat you might could use to try something. I haven't built anything since July so my head is fuzzy. lol But you might try MikeInside tutorial of how to raise the ground or floor, with the boolprop cheat to remove constraints of land.

boolprop testingcheatsenabled true
boolprop constrainfloorelevation false

I suggest you try experimenting with it on another lot to see how that goes, before applying to the lot you want to change.
ETA: You can look at MikeInside tutorial (pictures, too) of how to build with a slope around the buildings (house inside a mountain slope) and go from there.

Thank you! Will try once apt is warmer than the inside of a fridge, as that is where computers live.

Tried the cheat. The good news is that can get the ground to the walls. The less than good news is that the slope glitch is now in the walls, so I can't build my barns, etc.

Ah, that's too bad. You might have to do a little bit more experimenting with MikeInside tut on how to use that cheat to build split levels etc. It might take some doing but you might get something to work by reading that one, too. It shows pics of how to level out those uneven walls, which might help you to build a make shift barn.

I ran into the same issue when I was trying to build a basement for my house, here's what worked for me.
I built a pool against the house, then built the basement. Initially, the basement walls weren't as big as the ground floor and only bordered the pool. I then was able to adjust the size of the basement to suit my purposes. I haven't tried this method without the pool, but perhaps building a small basement room then adjusting is the workaround this issue. Good luck!