Dirt housing, bottles, cob, and sunken

Not exactly a new topic but part of several so ...

If you've read any of my posts you know I have a severe termite problem, not quite like the 10  foot mounds you see in Africa, but worse than any I've heard of in the states.  Both flying and ground types.  the land also has a moisture issue, being that it absorbs it and it can rain many inches, and then it will stay saturated a foot or 2 down for months.

I have this pit that is about 20 feet in diameter, used to be a circle but is a little less so now.  It is about 3 ft deep.  My idea is to build cob and bottle walls 8' above the top of the pit and use it for:  either an out door kitchen,  or  a green house of sorts with the idea that the in ground portion will help to keep it cooler, and the bottles will allow enough light to work.  I'm also thinking the bottles will help as insulation because they provide dead air space and with the cob for mass, the temp will fluctuate less.
It will of course have a drain around it and be slopped away on all sides.

There is no plan to use any concrete or footing per se, I'm thinking of some of the old houses that were dug into the desert.  I was going to use some vertical rebar to keep the walls plumb, and to provide a dome for some sort of thatched, or covered roof.

Love to hear some feed back and any ideas out there.  If this works I'd like to do more of them, we are developing an educational center in the midst of habitat restoration and sustainable ag blend so having lovely little "hobbit houses" that blended into the environment would be perfect.

I would start with a rubble trench, then an urbanite or some sort of stone wall to get you to ground level. and build up cob from there. Bottles are beautiful! but I wouldn't rely on them bringing in enough light for a greenhouse. Pick up some windows from a salvage yard to let the light in for plants. Rebar shouldn't be necessary in a cob structure, the walls should support your roof.

I love cob! it's beautiful! it's sculptable, it's fun to build, it's inexpensive, and if you're lucky most of it comes from right under your feet. Cob has so much going for it! I'm always looking for a cob project!

Thanks for the reply, sadly I have been unable to find any usable urbanite or rubble down here.  The few piles I've seen were completely unmanageable with huge chunks of concrete, mixed with nasty things.

As for ground level, the structure is intended to be sunk the 3+ feet into the ground, unlike most of the country we have too much heat and I'm looking for a way to grow lettuce and such during the summer.  We haven't been able to get any type of spinach to grow here either and it is a main food for us, and as much as we love other greens spinach is yummy raw as a salad.  I am hoping that because the building will be bottles all the way it will be enough light as adding windows will cause heat gain, but there is a provision in the design so if we must, there will be frames for them, that will start filled with 'plastic bottles, until we see how the light is.  Also the roof will be an option.

Where are you located?  As a Non Profit we are always open to volunteers, and would be delighted to find someone with cob experience

I understand that the structure is sunken into the ground, but if your walls don't sit on a solid base, your building won't last long. I wouldn't start Cob Walls below ground. A thick cob structure is good for keeping the cool in the summer. it's like being underground. that's why alot of the southwest tribes built with adobe.

Maybe with enough bottles you can capture enough light. That's up to you to decide. I might  would consider doing bottles low for the insulation factor, and some windows high in the building maybe even tucked under the eves to bring in more indirect light ... but keeping it as indirect as possible to not fry your leafy greens (I'm a big fan of leafy greens too =) ) your wall space will be thick enough, you may consider making your window a double layer by putting a window flush with the interior call and another in the center of the width of the wall; that would tuck it back out of the direct contact with the sun.

I'm in currently in Eugene, OR. I'd be happy to lend assistance where I can if your close enough.  I'd also be willing to relocate for the right opportunity. Where are you?

Eugene!?!  Too funny that is 'home' for me but I am allergic to all grasses, evergreens, and more, so relocated to the "Texas Tropics" near Brownsville at the southern most tip of Texas.

What is your 'regular' occupation?  Eugene is a tough place to make a living.  We have been hoping to get some winter workshops/projects happening, since it is infinitely nicer here in January than during the summer, which the last couple of years has been most of the year with our temps being 10-20 deg above normal. 

I understand the importance of solid footings.  It was more common to dig into the ground in the mid west where humidity and rain weren't an issue like here.  It has been very interesting to learn and account for the differences in climate, soil, and vermin that this area has.  I've lived all over the US including New Mexico so am quite familiar with adobe.  This building is definitely experimental and an attempt to push the boundaries as much as possible, I'm not attached to it lasting for decades, more just to see what can be done.  I'm expecting it to go up fairly quickly thanks to the bottles.  I did a little 3' high 'cord' and cob walls that were never enclosed at the top and lasted over 3 years including Hurricane Dolly!?!  I didn't even use real 'wood' but rather yucca trunks, which are semi hollow, I was quite surprised, at how well it lasted, no footings or anything, it was all experiment, just testing the cob mix and materials at hand