Stumped on foundations
I'm looking for what I think might be basic advice on a timber frames built on piers. I'm planning on building a timber frame sauna. The terrain and accessibility are such that I'm going to use piers that are anchored to bedrock. There will be a pier under each post.
I get that some kind of Simpson tie is needed to secure the frame to the piers and to make sure that posts/sills aren't sitting directly on the concrete piers to avoid rot.
I think I also need a threaded rod coming out of the pier to be able to attach the Simpson tie. It's best to get that rod in before the concrete sets.
But where I get totally stuck is what sits on the piers.
Option 1: Have the posts tie directly into the concrete pier (resting on some kind of Simpson tie). I could then bolt rim joists on the outside of the posts and hang the joists off that. I'm just not sure this is right - something feels off about this to me.
Option 2: I've also seen (mostly on slab foundations) sills that are lap jointed (with a mortise to receive the post). But them I'm not quite sure how to keep the sills off the pier and how to tie the sills to the pier. I tried using AI to help me figure this out but it suggested a bearing plate with some kind of sill gasket (the yellow arrow). I can see how the gasket would keep the sill off the pier and how the bearing plate would sandwich the sills to the pier. But in that case the bearing plate would block the mortise for the post tenon. I was therefore thinking instead of a mortise and tenon some kind of side plate could tie the post to the sill (the red arrow). Again, something feels off about this.
I'm just wondering if people can give me advice on where my logic is breaking down and/or which would be the better method (maybe one I haven't considered yet) to get this done.