Input needed on 30x20 1-1/2 cottage ext walls

[Sourdo]

Howdy all- I am in the process of building the mentioned cottage. So far I have the footer in and just poured the slab. The walls are going to be 6 foot for a nice roomy crawl space.

My question is about using 12' studs vs 10' studs. I want to have about 12 feet open over the great room. I have come up with a possible solution to help brace the hinge point on the top of the ext wall.
Look at the picture and you will see what I'm thinking. I have Autodesk Inventor 11, I am doing a 3d mock up of the cottage to help with some changes I have made. It's real handy software but unless your rich you won't want to buy it, about $5200!

BTW I live near Palmer, Alaska.

Thanks
http://picasaweb.google.com/lh/photo/jm1nUMhN1Qx8q0BkHf7pJQ?feat=directlink for image

[John Raabe]

I'm not an engineer nor do I know the design wind loads that might be expected on that wall. However, you have proposed a reasonable solution.

You have definitely stiffened the 12' x 12' wall on each side of the great room and triangulated that load at 4' o/c across the rafter tie. If that were a 10x10 wall area no bracing would be required. I would expect your braced 12x12 wall to be better braced and stiffer than the one that would be allowed.

Would look pretty good too!

[Sourdo]

Thanks for your opinion! I'm more concerned with earthquakes then wind. We get them now and then, just had a 5.3 last week centered 40 miles away. I could picture a tall unconnected wall swaying back and forth...

I'm going to run all-thread from the anchor bolts through the floor too some kind of brackets that will be bolted to the wall some way. Then run that up to the top plate and anchor as well. As that is what they do up here.... Only a matter of when not if, for the next big one.

[John Raabe]

Sounds good. There are brackets from Simpson to do just what you suggest. They will be embedded in the foundation and bolt into a double stud in the wall. At the top of the plates you can use other straps or brackets to have a "continuous load path" from roof to foundation.

A review with an experienced local engineer could spec these out for your specific earthquake loads.