Next design question. Wall length before it bows?

[phalynx]

In my previous question on ridge beam, I have learned how to calculate the roof load on a beam to avoid horizontal supports in the ceiling.  Now, the next question is, if you do a long beam, the side walls are only connected to the rafters and the beam but not directly to each other.  Would this potentially be a problem for the walls bowing or not staying straight?  Is there  maximum length to a wall before you need to tie it to the other wall?  A formula, math, etc?

[John Raabe]

If you have a ridge beam supporting the top of the rafter then the loads on the walls are resolved downward and do not put much outward pressure on the wall.

Thus you do not have to tie the walls together for the roof load, but you might still want ties as you do not want to have long unsupported walls taller than 10' - that is for a different reason - wind pressure on a long tall wall.

[phalynx]

Is there a general rule of thumb or calculation to know how often a tie is needed for wind?

[Don_P]

This will vary by state and even locality in some instances. It should be in or around section 602, wall bracing, in the IRC for your state, the wall chapter. In VA this section is state specific and requires a braced wall line at least every 50'. So if the house were 60' long I would need an interior braced wall line to break that up, as well as the exterior braced walls. Feel free to brace more frequently!

[phalynx]

That's a lot farther than I was expecting.  Cool...