Home Addition

The time has come to throw some thoughts out to the knowledge commons and see what sticks. Hard to pick a forum to place this one, it is being added to a tiny house, it will have natural and contemporary building methods, earth bermed, stone work, cob, etc.

A little -longish- story and some context.
I live in a small home I built myself using local lumber from a time in my career where I ran a local sawmill. It's a nice place and we (wife and I) learned much about building and living in small spaces. We have been in this house about 6~ish years. We have a detached bathhouse and some other hand-built outbuildings scattered about.
My work experience in general has been running specialty heavy equipment of various types. The last few years has been underground... I like facilitating moving water. Plenty of my close friends are journeymen level skilled tradesmen, as am I.

I have a sentimental attachment to building with rock, so the addition will have a rock foundation and at least a partial wall. I built a small crane trailer that dumps and can pick decent sized rocks fairly easily. We have good access to excavation/compaction equipment and are looking to invest into our own excavator for a variety of reasons, this project being one.

After a couple kids and years, we are ready for a little more space. The addition will be roughly 16'x32' and a portion will, out of necessity, be buried in a hillside. The deepest cut will be about 5' then tapering to about 2'. No uphill view, so the usual water problems exist.

Some rough drafts ideas, use large (2'+) rocks and concrete to form a footing. I have plenty of surplus slotted 6" HDPE pipe to throw behind it for some drainage. As well as sloping everything to daylight and backfilling with aggregate.
I have a few rolls of pond liner and conveyor belt material to toss behind the buried portion of the walls as well.  I am figuring foam board behind the wall itself, then liner, then conveyor belt to help protect the liner. Probably roll on some kind of toxic gick water stuff before the foam board too.

Once to grade, use slip form method to build up the foundation walls a few feet above dirt line. I figure I will be bored of stacking, hauling and dealing with rocks by then and probably set a concrete bond beam. Then switch to some other material for the remainder of the wall.

There is an adobe block maker within striking distance of my place, so that is appealing, or use a slip form cob using machinery to make it. I have played with machinery mixed cob a bit myself over the years and there is good local knowledge. Unless the rock work goes all the way up... which is possible but not likely.
Deep concrete footings with surplus steel pipe and I-beam for pole barn style framing to support the roof... all that material is on-hand already.

I will update this with more thoughts and context as time goes, but figured it'd be good to get something out there for discussion.

I am confused about
- what you have got?
- what you want to do?
- what you need ideas with?
Adobe or cob is no good near water.

John C Daley wrote:I am confused about
- what you have got?
- what you want to do?
- what you need ideas with?
Adobe or cob is no good near water.

I appreciate the engagement, I would probably be confused too.

-I have lots of rock, excavation and compaction equipment, construction and fabrication tools, plenty of steel, slotted drain pipe, pond liner membrane, etc.

-Build a roughly 16'x32' addition with a rock foundation with walls and a pole barn supported roof.

-Not particularly looking for any ideas per say, other than the usual internet critique of my ideas and other lenses. My own myopic view is just that. That will likely come along more as I am actually setting things up and showing a little more what I am up to.

-The idea is the rock will extend a couple feet above where the structure is buried, then a concrete bond beam and then cob or adobe. Long overhangs and the rest. I.E. if there is 5' underground there will be a 7' wall of rock with footing below that. That would only be in one back corner then it tapers out to about 2' of cut, and a 4' wall.  

I should probably also mention that the site is a building pad that was cut 10~ish years ago. It has a surface water ditch/drain cut at the top of the cut slope 15' above where the buried portion of the wall will be, so water concern is only subsurface. Honestly even the subsurface water concern is pretty minimal, but any time a wall is backfilled I like overly redundant drainage and water resistance. I'll make some video or pictures explaining my thoughts on water management better at some point.

What kind of life span are you building for, realistically? How might the structure want to evolve or retrofit along the way? Is it in THE right spot for that trajectory?

M I have a better idea know and it sounds ok.
It sounds like a project and that rock lifty is nifty. I guess its slow and low cost.
Have you seen the grappling hook claws foe lifting logs and rocks, they are easier for smaller rocks.
I have tried to make a small net like the side window protection on speedway cars to lift 2 foot sized rocks.