Has any one built a pole barn / post and beam / free standing deck in the interior? (Homer: garages)

[6.7traveler]

Hello, I am planning on building a 20x20 post and beam structure to sit a building on top of. Basically similar to a pole barn but with a flat top more like a free standing deck to sit one of my domes on.

Anyways, I was wondering how far I should put posts down into the ground. I have built pole barns and decks before but this was down in homer or the lower 48 and always went down 4 feet with the posts. I have read that frost line is about that here but can go deeper if there is early cold with no snow? I would hate to have a post or more heave out of the ground if this happens. If someone up here has some experience with a pole structure and depth I would love to know how it has held up over the years. Any problems with heaving? I have dug down 4 feet and don't have any permafrost and hit gravel at about that depth. Planning on going 4 feet down as of now...

Also planning on sonotube with 6x6 pt post embedded into the concrete, tapered off above grade and sealed. Not putting post directly into soil. I have worked with builders who set posts in concrete and others who set them in gravel as they claim the concrete holds water next to the post and eventually rots it away. Open to suggestions on this as well up here.

If post and beam structures don't do well up here I guess I'll have to go back to the drawing board, but I would love to be up in the air for a better view and have usable space underneath. I have seen quite a few pole barns up here as well. This is in delta junction area too if that helps.

Thanks!

[retiredinhomer]

Anyways, I was wondering how far I should put posts down into the ground. I have built pole barns and decks before but this was down in homer or the lower 48 and always went down 4 feet with the posts

I have had pilings and concrete sonotube get all jacked out of shape if they were put in any less than 5 feet. Maybe in downtown Homer on the water you can get by with 4 feet down. My deck was put in almost 20 years ago 4x4 post 10 foot long dug in with a backhoe wrapped with 4-6 layers of 6 mil visqueen (to keep the ice from grabbing the wood) I put this in at least 7 foot buried and the visqueen 8 foot wide just sticks out of the ground. We have a lot of clay up here and I am at 900 foot level.

[6.7traveler]

Originally Posted by retiredinhomer

Anyways, I was wondering how far I should put posts down into the ground. I have built pole barns and decks before but this was down in homer or the lower 48 and always went down 4 feet with the posts

I have had pilings and concrete sonotube get all jacked out of shape if they were put in any less than 5 feet. Maybe in downtown Homer on the water you can get by with 4 feet down. My deck was put in almost 20 years ago 4x4 post 10 foot long dug in with a backhoe wrapped with 4-6 layers of 6 mil visqueen (to keep the ice from grabbing the wood) I put this in at least 7 foot buried and the visqueen 8 foot wide just sticks out of the ground. We have a lot of clay up here and I am at 900 foot level.

I better not mention the builders name that I worked for down in homer then because he had us build several little pole barns / garages at 4 foot depth in sonotubes of east end road. This was last summer and I didn't stay long enough to hear how these have held up over the long term. They do have lots of heaving problems down there due to the clayey content of the soil. The guy that does the helical pier installs down there is a friend on mine and fixes many heaved posts. Anyways, thanks for the input. Maybe I have to re think this.... My auger is only 4 feet I may have to get a backhoe. I would love to use the helical piers but they are $$$.