My cabin is 16x12. Im doing to floor in PT  2x6. Since i have to cut the 2x6x12 down to 11'9" to account for the 2x6x16 ends I was wondering if instead of doing this


Would it maybe be a better idea to do it this way.


I have a very simple brain but the second way looks like it would be sturdier and easier to make it square and keep square.

I assume you are referring to the rim joist position.  I don't really see that it would make much difference.  If the 2X6 (1-1/2 X 5-1/2) are your floor joist might I suggest that you at least consider 2X8 (1-1/2 X 7-1/2) instead of 2X6.  That is not much foundation for a liveable structure.  The only way I would consider using 2X6 is if I doubled the support post or piers to limit the span.

Yes the rim joist. I can never remember the names of all the different components of a house.

As for the 2x6 over the 2x8. Im actually following more or less Johns Little House Plan. In it he has a 12x18 that calls for 2x6's. If money where no object I would definitely use 2x8s. I just cannot afford the extra $4 a board. If I can get 15 summer vacations out of this place I will be happy.

I don't believe it matters to building code but I was taught to use option 2 and to weave framing whenever possible, it makes it a little tougher to rip apart.

Max span on 2x6's is around 9.5', unfortunately physics doesn't respect our budgetary constraints  .

"unfortunately physics doesn't respect our budgetary constraints   "
Im working on it 

Luckily I only have to span 7'4". What do you mean "weave framing"

Weaving is what you are doing in option 2. In option 1 all the connections in the rims perpendicular to the joists are in withdrawal. In option 2 you have switched the end connections to shear while the joist to rim connections remain in withdrawal. The best example that pops into my head is the 2 top plates at an intersecting pair of walls. The lower top plates stop at wall ends, the upper top plate then laps over the walls the other way, weaving them together and installing nails in shear on both sides of the intersection.

Not everyone may be aware that the Little House plans have the floor joists cantilevered over the beams, reducing the joist span. Just keep in mind that the plans can do that because it is a lightly loaded structure with minimal loft. Changes that would increase the upper load, or heavy snow loads might require adjustments.