The north and south sides of my building are post frame walls. But unlike regular post frame i have developed my own system for the foundation/ground connection of the wall. I developed this system on my last house i built and it worked out great, it is further improved on this house. A major benefit of post frame construction is not needing a full concrete foundation, saves cost and time. This works out great for a barn, not so good for a house. The reason being that you need something to contact the ground between the posts, most are just using a treated wood skirt board and gravel. I think this system i developed would be great for a lot of folks
Here is how it works. It is very similar to what i did on my berm walls, with concrete piers and a 6"X6" grade beam poured on top. However in this case the 6" wide beam isnt a big enough footing so the piers are actually carrying the load of the posts/building and the grade beam is just a filler between the wood and the ground, this gives you a foundation that is rot proof, easy to build and cheap and uses minimal concrete, no fancy formwork. It also includes a perimeter skirt of insulation built into it, as is commonly done on regular concrete frost walls for the buildings thermal efficiency performance and to keep any frost heaving from going on under the grade beams, it works like a shallow frost protected foundation.
Here is how its done:
1. Dig piers (i chose every 6 feet apart) Make sure your piers line up so that you have piers aligning under your posts for the structural load. I make 12" holes with a
tractor auger going down below frost line and bell out the bottom for a larger footing.
2 Pour concrete in piers, set height of piers 8" below the proposed top of the concrete wall. Allowing 2" of foam plus 6" of grade beam on top = 8inches
3. push a rebar down the pier and let it stick out a foot or so
4. after the concrete sets up, install 2' wide perimeter foam (the pink stuff) laid flat on top of the ground and piers. I pushed mine to hang inside my building (see top view picture below), as my locations climate can get away with frost protection like that and that will protect my foam from being outside the building.
5. Cut holes in the foam over the piers. This allows the grade beams concrete to connect with the pier and tie in the rebar.
6. Pin down the foam with some rebar stakes, this keeps the foam from moving while you are setting up forms and pouring on top of it
7. Pop chalk lines down the foam where the wall/grade beam goes
8. screw a cleat board into the foam down the line where it needs to go, the foam is strong enough to hold it if you are careful.
9. to the cleat board attach your 6"X6" concrete forms, using the same boards used on the earth berm wall pour.
10. install one #4 rebar down the inside of the forms
11. pour concrete into the form
12. set in concrete j bolts (any bolt works really) into the concrete every 6', Make sure to set some next to where your post will be located. These hold down your sill plate just like on a regular stick frame wall. My posts sit on my sill plates and are tied to it with cheap metal flat straps. I do it this way because its cheaper than buying post anchors, but you could choose from a number of anchoring strategies to suit your preference.
And this grade beam is tied into the grade beams on the berm walls with a rebar, they are poured at the same height. Anyways, i never seen anyone else doing this, but i really like this system for the wall/ground contact of a post frame. Maybe i should name it something. Pier and insulated beam post frame or something like that i dont know... Ill have to get some better pics of it but its covered in snow right now