I have been reading and studying timber frame construction methods for a couple of years in preparation for building my own home. I have read the basic how to textbooks and have a pretty good idea of the geometries necessary to produce a strong traditional frame. However, when I look at the photos in books such as Morris's Timberframe Plan Book, I see many walls with no knee braces whatsoever and timber spans much longer than those recommended in design books. I can only conclude that these structural deficiencies are possible because the SIPS or exterior framed walls provide the support that the frames themselves appear to be lacking, and that many of these frames are primarily there for appearance.
As i work on a design for my home I find it difficult to get enough open floor space and room for doors and windows if I stick to the rules in Sobon, Benson, and Chappells books. I had planned on doing this myself but I am faced with either abiding by the rules or stretching things a bit and relying on the walls for integrity of the frame. I'm just wondering how others have dealt with these problems and if there is any resource that discusses the modifications that can safely be made to the frame when relying on the combined matrix of frame and walls. I will be using a standard 2x6 wall that will not be an infill, but totally outside of the frame. Thank you for your comments and enlightenment.