I have decided to make several "roundwood" post and beam structures, or at least using raw log posts as supports, but I can't figure out how to anchor them to the ground. I live in the mountains of TN and it is very moist here, so I am worried about moisture from concrete or stone seeping up into the logs via concrete piers and I plan on doing a few for porch posts outside. Any suggestions on anchoring?
My ideas were:
1. building a high concrete pier and running at least 3 piece of rebar up through the post a foot or so, but its still sitting on concrete. Maybe putting tar shingles between the concrete and wood? Steel plates between them?
2. Then I saw the 2nd and 3rd pictures below and thought about using knife plates or brackets. I want to do a couple supports that have angles like the 2nd picture, so a bracket of some sort seems necessary, but I know they are incredibly pricey and hard to find. Know where I can find them? And I don't feel like just rebar is strong enough to brace such large posts (12-20" in diameter)
3. My other concern is I have plenty of yellow pines on my property and was going to use those as the beams, but would they be too soft to use as posts, even if I coated them with boat varnish or (god forbid) treat them with nasty stuff? And I didn't know if mixing harder wood for posts and softer wood for beams would work. I might be able to find some Black Locusts, and I know that would solve my problems, but it would be easier to use other wood like Oak, and I would like to eventually be able to show others in my area that we can use local wood. Black locust is getting rather rare here.
Any ideas would be very helpful. I plan on getting Ben Law's book "Roundwood Timber Framing," but from what I have read he doesn't address anchoring in a vey detailed way or concerns of moisture seeping into the posts much.. and I didnt see any info on outside porch supports at all.
I would really like these structures to last a while so anyone with experience working with large wood who has any advice at all would be helpful.