I was a builder for several years in Southern California and familiar with slab on grade and raised floor foundations - formed and poured quite a few back in the day. I am in the planning stages for my personal cabin up in the Sierras. My preference is to maintain the natural condition/grade of my building site. Aprox 24x30 foot print for the cabin with about a 12" of grade change over 30'. My experience with local Building codes in my region require continuous perimeter footings and that is my intent.
So my concern is how to form this up due to soil conditions. Having put in well over 300 fence posts on my property, I know I can expect in many cases to hit tough Decomposed (ish) granite at 6" to 12" from the soil surface. This will make driving wood or even metal stakes impossible. My neighbor who built on a slope with a walk out basement had to use dynamite to excavate back into his slope but mine is a flat site build.
Here my thoughts on a solution :
1. Figure out a way to secure batter boards to create string layout of foundation. (open for suggestions on this)
2. Excavate for raised floor foundation with perimeter stem wall. (I am assuming a backhoe will be able to power thru the hard DG sections and hopefully no full on granite at 24" deep).
3. Set rod with extended verticals for block stem wall and pour concrete footings to grade.
4. Build perimeter block stem wall utilizing batter board string layout and eliminating need for stake and board forms.
5. Interior pier supports could be possibly be poured complete with sono tube forms sunk in to excavated hole and further supported by sand bags or?
Any insight or similar experience and solutions would be appreciated.
I made up some brackets out of steel tubing i had. The form boards then hung off the bracket. I had the same problem as you, not able to pound stakes into the ground.
https://countryplans.com/smf/index.php?topic=14817.msg193299#msg193299
I use a Hilti percussion drill for stuff like that, mines a TE70. We have a lot of granite, well gneiss, and decomposed stuff that is pretty tight. I have up to 1-3/8" x 2' long drills, 4" wide clay spade that will eat through the decomposed stuff. The various drills allow me to set stakes. Then long chisels for eating up tough stuff, I wore out several demoing concrete on the last job. The big drill bit is the size used with dexpan, a high expanding grout, drill like you were going to blast but mix and pour the holes full of dexpan and come back in the morning, it'll fracture the rock, chuck up chisels, remove and repeat, not cheap but blasting isn't either anymore. Works if it is a relatively small amount of solid rock. We cleared a site over the past couple of weekends and I've been bringing the logs home, milled the first load over this weekend. There are several truck bed sized rocks on the surface, could get interesting when we start digging d*. And yup, more than once I've just poured the trench to near grade and started block from there rather than fuss too much.
Thank You that is helpful information from you guys!!