Expert: Ted Barnhill (Principal, Design45 LLC) - 7/20/2007

Question
HI, I,M PLANING TO BUILD AT TOK ALASKA,IT'S COLD THERE.
WAT I HAVE TO LOOK AT IS THE WEATHER FACTOR .
IM GOING TO USE NEW RAILROAD TIES FOR THE FOOTING WITH
2 OF THEM SIDE BY SIDE ABOUT 18 INCHS THEN STACK 3 MORE
ON TOP.
THE SPAN WILL BE 20 FOOT USING 2BY12'S DOUBLED UP ON 2 FOOT
CENTERS.
I PLAN ON USING ALL THREAD BOLTS THROU TH TIES AND R-38
INSULATION IN THE FLOOR.
THE EXTERIOR WALL WILL BE 2 BY 6'S WITH R-38 AND GOING 18
INCHES BECAUSE OF THE SNOW LOADING DURING THE WINTERS.
EVERY 4 FOOT POINT WILL HAVE A DOUBLE STUD. WHERE  I CAN
NAIL STRAIGHT IN THROU THE PLYWOOD AT THE EDGES.
HMM
BECAUSE OF EARTHQUAKES AROUND HERE I,M THINKIN ABOUT TIEING
THE ENDS OF THE 2 BY 8'S IN THE CEILING INTO THE WALL STUDS
INSTEAD OF RESTING THEM ON TOP OF THE WALL STUDS.
THE PROBLEM IS THIS
I DONT WANT IT TO FALL APART IN THE MIDDLE OF A QUAKE.
CAN I GET RID OF THE 16 PENNY NAILS AND USE SCREWS AND
BOLTS INSTEAD.  AND LOTS OF GLUE  HA HA.

Answer
I don't quite understand your question, but some comments:
- It sounds as if you are not putting footings down to the frost level.  Depending on your soils, you may have differential heaving.  Check into shallow frost-protected footings for another way to do it without deep excavation.
- Direct gravity bearing of rafters/trusses to top plate is standard framing practice for good reasons, including longevity and fire blocking.  You can use metal ties for additional uplift/hurricane/earthquake stability.  See Simpson/Strongtie, or talk to a local engineer.
- I think you mean 16" on center, and you don't need a double stud for nailing sheathing, just lay it out accurately and you can nail both sheets into one stud.  It will be hard to get R-38 into 6" walls; if you mean fiberglass batts, it's R-19.

Good luck.