I've seen your pics, impressive.

To make $ on siding, s&f, gutters,,,

there is a fiberglass wood reenfocing product I have seen used on wood tower bases , I am not even sure you need that



I think it's a barn , I would cut 6x6 to go on either side of the post that is there and get them in snug on top of that concrete wall that can help carry your load as insurance and run some threaded rod through to tie all that together with nuts and washers on each side.

then something to stop that from rotting any more , wire wheel out the loose stuff and treat it so it doesn't degrade more.
maybe something like an asphalt fence paint

or make your own so asphalt fence paint

get that wood sealed down a foot or so below grade and paint it up to the top

it sort of looks like that top plate and beam are not treated lumber might paint all that also.

well thats my thought on making a barn work for a bunch more years without dropping a fortune on it.

I think I would do one more thing , dig that down around a foot all the way along and lay a drain tile and cover it all with stone so you get drainage and keep that dry as you can for the future.

I just put another post beside the rotten ones and connected them together.

You know what? I was thinking that you could put some blocks between the concrete and bottom of building. That would keep it from tipping over.

Not sure if you have room, but Techno metal posts work great in applications like your situation.

also wouldn't hurt to tar from a foot below ground to about 2 feet above

water soaking into concrete and freeze thaw is hard on it.

This is a very real possibility and it makes things a real pain.

Creosote or osmote for wood in the ground.

There was a large building here on the barrier beach that was built on pilings, a storm went through and most of the sand washed away, with some of the pilings hanging in the air....

They dug down alongside the hanging pilings, dropped another one in next to the hanger and bolted them together...building is still there....If you end up doing something like that, I'd dig down a little below the rot and soak it with drain oil...

Temporary shoring to support the roof. Add a pressure treated sill plate on top of that concrete wall drilled and anchored to the concrete. Cut the post to sit on top of that new sill plate. No more posts in the gound. Use cut concrete blocks and mortar to fill in the concrete gaps where the posts used to be. I have half a dozen of these that make shoring easy: https://ellismanufacturing.com/prod...msclkid=a743d12b13d61caf3880bb31f1affc14

You need to jack with a 4x4 on a bottle jack and then support what you lifted with these shoring posts.

- Jack and --shore both sides of onen post at a time.
- Cut the post off 1-1/2" above tour concrete wall.
- Slip in the longest piece of pressure treated 2x that you can under the post as your new sill plate.
- Set the post down on your new pressure treated 2x sill plate.
- Drill and anchor the sill plate to the concrete wall.
- Nail the post to the new sill plate or use any of the structural galvanized post bases.
- Move on to post #2.
- Go back and fill in the gaps in your concrete wall.

Are those concrete "walls" around 6" thick? Hard to tell from the pictures, but if so, your fix is as simple as leaving the rotted posts in place and putting new ones next to the old. Of course, it would be nice if the concrete walls had a decent footing under them.

Support it with a new post. Use a sawzall to cut old one out put new one in. Concrete screws and a bracket of sorts. Good to go.

Get on utube, there are several videos that show products and installations. Basically metal plates that you hammer into the ground right next to the posts and then screw the plates to the posts. You can even drive them next to posts that are set in concrete.

I like this idea!

Like this one better!
DON'T FORGET TO GO BELOW THE FROST LINE DEPTH!