Sizing Headers in Older Home
I wouldn't know about California but in Texas back in the 50's, the rule of thumb was to take the width opening in feet to the next largest number and double it. A 3' opening would be a 2x 6, a 4' opening would be a 2x 8, a 5' opening would be a 2x 10, a 6' opening would be a 2x 12. All would have 3/8" ply in the middle for a spacer as the lumber dimension for a 2x 4 was 3 5/8" x 1 5/8". For a few years in the mid 60's, the dimension was 3 9/16" x 1 9/16". Shortly after that, it's now the dimensional size we have today.
Lumber is still bought and old based on the nominal size or in better words, when you buy a 2x 4, you are paying for a 2"x 4" piece of wood but you're only getting 1 1/2'x 3 1/2". The price is in dollars per thousand board feet. The box stores have taken the guess work out of it and sell it by the each. Builder yards are quoting price per thousand but invoice at price per each. In the case of a stud, which many are used in a home, that can mean a few dollars profit more because of the math.
In regards to the trimmers as you call them, you need to check on the local code. California pretty requires seismic anchors at all locations. You'll probably need to use a steel hanger at window openings. At least, that's what's on the stuff we see on plans out of California.
Last edited by TrapperL; 09-02-2011 at 12:11 AM.