Framing options for barn - shop + living space

[old_guy]

The first structure on our Tennessee property will be a gambrel-roofed barn, with 2x6 stud walls.  It will be used for storage and workshop, as well as living quarters.  Temporary living for us until we build the house, and guest quarters later.  We are currently planning a 48' x 28' main structure with a full second floor, and with 12' or 14' wide 1-story shed wings on both long sides.  One wing will be roof-only, the other will be enclosed for living area.  Upstairs will be storage, play area, a couple of bedrooms, and a full bath.  28' floor trusses are planned for the 2nd floor, so there will be no posts needed for support.

Our current plan is for one end of the main barn to be living space on the main floor.  If we allocate 20 feet of that end for living space, that will leave a 28' square area for garage/shop.  All living space is expected to have wood sheet sub-floor over 2x joists.  Garage/shop floor will be gravel now, concrete later.  The main structure will have a full perimeter footing and concrete block stem/foundation walls.  Sheds will be supported with posts on concrete.  Perimeter foundation will be contracted and completed well before we start the structure.

Goal 1 is to get it weather tight as quickly as possible this summer, as my crew will be few and temporary.  I can then finish the inside stuff myself, with some help from my son, regardless of weather.

Questions:  With 28' of each long wall being 2x6 studs standing on the stem walls, and the remaining 20' having a raised floor, what is the best way (keeping in mind goal 1) to frame those walls and have the top plates be (and stay) level?  I can shorten the studs in the floored area by the width of the joists and thickness of subfloor, and all should be good, but as the joists shrink there may be stress between the wall sections or other issues (Perhaps I worry too much?).  I could also just build the stud walls the entire 48', and add floor joists later.  The joists could be sistered to the studs and resting on the sole plate.  I expect I would need blocking to support the edge of the floor sheets, and maybe between the studs just above the floor for baseboards.  I can add that by myself after weather tight as I have time.

So – I want as much under roof as soon as possible, (don't we all) and want to put joists and floor in one shed wing and part of main floor.  What are good ways to approach this?  If my current thoughts are goofy, or there are other good choices, please let me know.

Thank you.

- John

[Don_P]

Is there a reason not to put the living areas on a slab that is the same elevation as the shop? They can be thermally broken from one another. The wood floors will complicate repurposing the space after you move into the "big house" not to mention complicating construction. Check into trusses for the second floor/roof. If they can do it that will speed that part of the job up considerably. You're overworrying the joist shrinkage issue. Trying to fireblock that area later if you drop the studs down to the sill is a royal pita.

[MushCreek]

 I would recommend finding the funds to do it on a slab. My barn is the exact same size, with a similar usage plan. As for the loft, have you looked at barnplans.com? I used their plans. It makes a good-looking barn, and the method of framing the loft is well-suited for DIY.

[akwoodchuck]

Never used this product, but it seems like a good DIY way to get your shell put together in a timely manner:
http://socketsys.com/

[Don_P]

Been there, I don't think I would do it again with their kit but modifying the concept would work.

[old_guy]

Thanks, everyone.

I briefly considered a slab in the 28x48 main structure, but rejected it for a couple of reasons.  First, the $6k - $8k for the slab, plus insulation under the living area, will be tough to find this first year.  We have really dug a little deeper than comfortable in the money pail for the current plan.  The pad for the barn is all virgin soil except for one corner of the 28x48.  We can dig the footing down to virgin soil, but that corner would need to be filled and compacted to support the slab.  I am concerned about settling.  Again, maybe I worry too much.

The ground under the 14x48 living space under the shed roof slopes seriously away from the main structure.  I had planned joists for this floor to avoid dealing with the sloping ground, and the space under the joists with the stem wall and the slope would leave plenty of room for running water supply and drains.

I need a wall along each of the 48' sides to support the 2nd floor and the roof.  I need also to transition between the shed and main barn living spaces.  Maybe I can lower the block wall to ease the transition.  Don - I had considered the fire-block issue, but had decided it would be simple.  Your comment has me rethinking that effort and, like (almost   ) always, I accept your experienced input and will almost certainly not add the floor joists after erecting walls.  Tomorrow I will rerun the numbers with the full slab, and see how much it will set us back.

Mushcreek - I am seriously considering the barnplans.com plans.  I feel it would be better to have the dormer roofs break at the same place as the barn roof, but am comfortable with the engineering of the trusses and the simplicity of building them on site.  I have seen your barn in a couple of posts, but have not seen a build thread for it.  Is there one?  I would appreciate taking a better look.

Gonna do some more work on this tomorrow.  I truly appreciate the great suggestions,

- John