I'm building a cabin and I really would like to not use big machinery if possible. I have the stumps all down right to the ground line, but I'm hoping to build like that. I am using pillars and hope to have about 4' clearance to use the space as a root cellar. The Land is on a slight angle so only part of the cabin will have a root cellar my question is can I just build like so or do I need to pull out all the stumps? I can't see why I couldn't, but maybe their is drawbacks I'm not aware of. What are your thoughts?

I'd mostly worry about termites.  We have stumps under our house and I worry about that.

As mentioned termites and other bugs that would then infect your cabin could be an issue.

Another might be settling over the long term as the stumps and roots rot under ground. This could cause your support pillars to move and stress the cabin construction.

In the end though, I suspect you could do it. You might want to treat the exposed stumps by charring them to reduce insects attacking the exposed wood. Then monitor the cabin in the decades to come.

You can definitely do it,  but I suspect that if the cabin is intended for long-term use that you will regret it.

It's easy to span over stumps with piers and floor joists.   Just stay way clear of the stumps when placing your piers.   The stumps will dry out under the floor and will eventually rot.  I've seen many cases of folks who've done this...  the problem is that years later they regret not taking the time or spending the money initially to remove the stumps.   It's very hard and expensive to remove them when a house is over them.  

If you don't have access to a backhoe or excavator you might try burning the stumps, but that is a very difficult task.

Stumps are always a pain in the ass.  There just isn't any easy way to remove them, particularly if they are from old huge trees.  If you had a couple of years you could drill the stumps full of holes and inoculate them with mushroom spawn.  You might even get a crop out of that if you found the right mushroom cultivar for the tree species and for your climate.

What is the soil profile like?  if there is a layer of stone beneath the soil less than a couple of feet down, that might be your salvation.  You'll need to excavate down till you reach that stone layer and then build your forms and pour your piers right on top of that.  Once done, you'll back-fill around those piers --- or carve out your root cellar at that time.

But if you are going to that much work to excavate down to pour such concrete piers -- why not just dig out the stumps?  You'd need an excavator either way.  Unless the stone is less than 2 feet down, you don't want to be hand digging your foundation.

Depending on the size of the cabin, I've seen people build with jacks attached to the corners of the building so that you can crank it up with a couple of turns every couple of years.  These aren't cheep, nor are they very stable if you live in earthquake country (like I do).  Basically, the cabin floats above the ground on these jacks.  Every so often you go out there with a level and crank up one corner or another to bring the thing back to plumb.  Its basically the same system as you'd have in a camper or motorhome, just a bit more permanent.  

If it were me (and I planned on keeping that cabin for 30 years), I'd bite the bullet and dig those suckers out.  $2000 spent now will save you a lot of frustration down the road.

Best of luck.

I echo what others have said in that you would be better off to remove the stumps.

However if you are opposed to large machinery, you could spend some time researching how the pioneers here removed stumps. There s amazing ways they did so. Kind of a remove-the-stump, but-not-with-heavy-equipment sort of way.

I wouldn't leave those stumps in my building site either.

At this point my "innovative" advice is a bit useless to you, and the easiest way to get those stumps out now is with an excavator with a "thumb" bucket.
In the past, the innovative thing I have done is to cut the tree off at about chest height, this leaves me a big lever that is part of the stump. Then I dig around the stump and cut the roots off, a couple of feet from the base if I can get away with it. Once all that is done, I hook up a nice come-a-long, usually a 4 to 8 ton model. I like to get a solid anchor point and then start the pulling. If I can do it, I'll leave it uncut, do the same thing with the roots and then use the really long lever to pull it over. Once it's on the deck then I'll go ahead and section it up as normal. The best part is finding dirt to fill the hole back up.
With my introduction to hugelkultur here on permies, I now have something much better to do with the stumps than build a slash pile and burn them.

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Thanks for all the advice. I am going to remove them. I can rent a mini excavator for a week and it will cost me less than grand. Cheaper still then getting someone in. I loved the video of the work horses pulling the stumps! We have oxen out here, but to find someone to do it. I might be bale to find someone who wants to practice old skills? The cabin is for a long time, it will be my home for some time. THe trees are pretty small as the land had been cleared about 25-30 years ago, so the trees are not much bigger than 12 inches. I did have the stumps all sticking out for easier removal, but then I thought I could keep them and without prior thinkg cut them right down to the ground. Learning curves.

Stump height does not matter if you are using an excavator.

I rent a lot of equipment because for some strange reason people seem to want me to clear land for them. I know it sounds counter intuitive, but with stumps, bigger is better. I know money is money, but with a small excavator it might take 4 times longer to pull a stump then it would take to pull it with a machine twice as big. The cost per week is twice as much, but you get way more done. This is especially true if you might run into rocks.

To get the most from your excavator plan on using it a full 40 hours. Make a list of things that HAVE to get done, things you really hope get done, and things you wish would get done. They do a fair amount of work so get the work out of them by pre-planning. Also, you are not paying for the starter so shut it off and never let it idle, those minutes add into hours, and hours you are not getting work done. Also watch the weather, without question as soon as the machine arrives, its going to rain...Murphy's law. Work the wet sections first. Again planning work with the machine around the weather really pays off.

If you run out of time with the machine, assess whether or not to keep working it. The biggest mistake you can make is sending it back. It costs a fee to have it delivered and you might not be able to get it again for awhile.

Schedule the rent well in advance. Availability of the machine you want does not always coincide with your time to work it. Last year I waited all summer for a big bulldozer that another renter kept, and kept, and kept...

There is a lot of hidden costs with rental equipment. Delivery fees, diesel fuel, break-downs and repairs. I say break downs because, while my rental company pays for them, the question is can you sit by doing nothing on vacation from your real job as you are waiting for parts to come in. I have dealt with this before and it sucks! If you are using vacation time from a traditional job, be ready to be flexible because I have never rented a piece of equipment yet that did not break.

Sometimes it was my fault and so plan for 30% above the rental price. Last summer I rented an excavator and cleared 18 acres of mountainside. In dong that I absolutely stove that excavator all to crap. I spent my own money fixing it only to have the rental company say I scratched the counterweight and it needed to be repainted. ($300). As I said, a lot of hidden costs with rental equipment.

But it makes sense. They are actually pretty cheap IF you get the seat time in. You have to work them, rain or shine and from dawn to dusk. Usually I run out of days before I run out of hours.

Makes sense. It is nt too small an escalator so I think I will be ok. If it doesn't work, I get a guy down the road. I really want to try it myself first. I also need to work on some gardens I am clearing up for new gardens this year, so if the stumps are too much I can get that done at least. But I totally get what your saying. I woudl ideally like to be moving in this summer but if it doesn't happen till fall, I m ok with that. The terrain is pretty mild to what your are describing, I am in a place where we dont have mountain sides and we have rocks but nothing too huge here. It really is an ideal place to try an exscavator. Last summer i dug out a septic tank and I had to try aand find it as the previous owners never knew where it was. I had to dig holes all over the place!! It was actually pretty good terrain to do, I did it by hand! If I come up to something when I use the machine, I will re try something else. This whole thing is a major learning curve for me.

I too agree that it would be best to remove the stumps under the house.  

As for the rest of the area I have always left the stumps to rot.  

Our area is a combination of sand and compacted clay.  In both situations the rotting wood under ground provides channels for water to flow deep in the ground and the underground wood acts as an inverted hugelculture helping to maintain a moist but not soggy environment for roots ( I do not irrigate/water my plants).

The area will very quickly be overrun by weeds and sprouts from the tree roots but this can be controlled for a couple of years by goats and poultry - both of which will also fertilize the area as they smooth it out and keep weeds and brush down. Poultry will appreciate any insects or larvae they can dig up.   Then when the area is ready for you the animals can be moved to clean another area or eaten.

It is a very long term approach.  It took about 8 years at my last small farm to create rich black soil from sand but it was worth it and also saved labor and money.

I have a much smaller area in my new urban lot that has taken two years AND I don't have the benefit of small livestock to help me.  But the area is starting to show some growth of mushrooms and green plants