I've re-opened this thread because I am going to be building a very similar timber-frame structure. After reading the replies, I need to re-think how I am going to attach the posts to the concrete footers. I was just going to embed the post in the concrete, but I think I will stay away from that. Does anyone have any more to add on this subject?

Also, I will be using an 8x12 tie beam and king posts, 8x10 rafters, and 8x8 purlins. The discussion of "overkill" came up, and I am certain it applies here. I am more concerned with having too much weight from the rafters and purlins than would cause structural problems. I like the classic aspect of timber-framing "over-building. Being an open-frame design, I would like to end up seeing a "sturdy" structure complete with aspects of traditional joinery. But I certainly don't want to build something that is structurally unsound.

Does anyone have any thoughts on using 8x10 rafters with 8x8 purlins for a northern Wisconsin application?

Thanks, Tim