Bottom Plate Lean To Question

[nickking2785]

Planning/about to begin building a lean to off my existing cmu block garage/barn.
I have a really big area of asphalt coming into the existing garage and along the sides of it.
I plan on coming off the side of the garage 11’ by about 30’ along the garage. I feel like I have everything pretty much figured out just wanted your advice on something. I plan on digging post holes (42” frost line) every 8’max and pouring concrete flush to the asphalt for support. My question is what would you use for a bottom plate of that 30’ long wall. Or would you put 4x4 posts on that footings I’m installing?
The lean to will be completely enclosed. The 30’ long wall and the back wall will be sheathed and sided and the front will have a garage door.
I’m considering putting 1/2” rod in the post holes when poured and taking 2x4 or 2x6 treated lumber and running 2 of them on there sides for the bottom plate. At the 1/2” rods I would put a plate and bolt them down to the footing. Hopefully that makes sense?
The other idea was to put 4x4’s at the post holes, and then just run your typical treated bottom plate between the posts and frame off that. Let me know what you guys think. And since this is just a straight 30’ wall I was just going to frame with 2x4’s 16” centers and double top plate and just land the rafters on that. And get the clips to lock them down.
Appreciate the help guys

 

[jack stand]

Have you investigated how flat and level the pavement is?
You mention that this will be completely enclosed, I guess my question is getting a good "sealing" of the new wall to a somewhat irregular surface - the asphalt, and having the wall bear on a more or less what is temporary surface.
I'd be inclined to go with your posts/concrete piers and appropriate beam across the posts to support the roof and at that point the wall is only supporting whatever insulation and wall finishes you use.
Basically you'll be fighting water running across the driveway entering the building, and then there's the doorways.

 

[billconner]

Not sure how you deal with frost movement of ground between piers, which presumably should not heave.

 

[nickking2785]

Jack stand I appreciate that very much. I agree with what you are saying. If I put to much weight on those walls that are resting on the asphalt it will settle and get messed up. I think the posts and beam at top is the way to go

 

[jack stand]

HiJack stand I appreciate that very much. I agree with what you are saying. If I put to much weight on those walls that are resting on the asphalt it will settle and get messed up. I think the posts and beam at top is the way to go

Nick it's not the weight as much as it's the pavement. There's no telling what the base under it is and eventually it's going to crumble apart as the asphalt that's binding it together evaporates or whatever it does. Then as soon as it starts to take in water.....
It's much better to rely on your new footings for the long term. An 8' post spacing would minimize the beam size and only be another post or 2 in that wall. You might think about using a 4x6 in the 6" dimension. You could then cut in a seat for a pair of 2x's for the beam. It's always nice to have actual bearing rather than relying on nail, bolts or other hardware to support the beam.