Yeah this will be very unconventional framing.
My building sits on 12 cinder blocks. I framed the floor with 2x6, 16" o.c. with a doubled strong back down the center under the 2x6.
Could not afford concrete so this was the alternative. However in hindsight I would gladly pay extra for concrete vs. Trying to level out 12 separate sets of blocks!
But what's done is done. I could have done poles in the ground but knowing g it was going to have a wood floor , I decided on blocks that let's my floor be at least 16 inches on the high side of the grade to allow enough air flow under it to keep it dry.
So, the framing will mimic a pole building. 6 trusses on 4 ft o.c. and a 4x4 post uder each. The corners will be 4x6 posts.
I thought about stick framing it but seemed like overkill with 16" o.c. studs and then girts every 24" to screw the metal to. So 4x4 posts 48" o.c. to support the roof trusses and roof.
I should have built my floor 15'-9" × 19'-9". That way I could screw my girts to the outside of the posts and had a 16x20 overall not counting g the siding. Then my 16 ft girts would be long enough.
That's why I was wondering about just banding the top 2x8 into a 1 1/2" notch cut into the tops of the posts and attaching the girts in between the posts (like a wood privacy fence is built).
My question was will doing this weaken the structure? Also I was wondering how I was going to notch all the posts and girts to except the diagonal bracing for the walls.
I suppose I could notch the inside of the posts and run the diagonal braces on the I side Instead of the outside lime normal.
First, is this structure permitted or having building inspections done ? If so, your inspector has the ruling authority here. A inspector over rules all internet advice ya know.
To me at least, unless the posts are put in the ground as conventional "pole" barns are, mounting them on a wood deck is sort of "faking" it. Because the intent of poles/posts being put in the ground is to give the structure better wind resistance strength.
Whenever posts are just set on a wood deck and even if using the good Simpson post base ties screwed down to blocking between the joists, their vertical "side to side" strength of the vertical posts has been compromised.
IE: Set a 4 " x4" post screwed down to a 3/4 inch plywood deck using a Simpson anchor base plate and I will bet you a $100.00 I can shake it loose with my bare hands. Run the same post down between the floor joists and "block " it in, I cannot shake it loose so easily, but I will still be able to move it some. Dig it down 36 inches and hard tamp it it dirt or even pour concrete mix around it, I will still move it some by "flexing " it above ground but it will not loosen up from its base.
So IMO with your present build, just sandwiching studs in the wall using 3 side by side nailed tightly together (triple studs) will serve the same vertical load bearing support as a 4"x 4 " post (3.5 x 3.5 ") will. They would be much less likely to wrap in the future also, like a treated 4" x 4" post will.
And to your 3 " total loss of out to out framing width/length now, is there anyway to consider just setting your walls back inward 1.5" on the deck now ?
Unless you are using REALLY specific dimension equipment inside the building to where one cannot give up the 3 inches inside, I see this as your best option. ( just do not figure on using a 16' wide roll up door)
And to your "notching" the posts for your top wall band and putting all the girts "inside to inside" of the posts. IMO I see no significant loss of vertical/side to side weakening of the structure by doing so.
BUT, as my sketch shows, it will be a LOT of extra work and fastening for you to do the notching/mitered cuts of the diagonal bracings. And once you have "notched" a 1.5" deep 2" x4" in to a 3.5" thick post, you have compromised the post strength also.
As already stated, may want to also consider just stick framing the walls. Maybe go 24" O.C. stud walls with double studs under the trusses if that makes it suitable.. Good Luck and JMO.
