Green Horn, Steve Chapell's book Timberframe workshop outlines many of the calcualtions and guidlines for design. My being a mechanical engineer helped me to understand as I've worked with that stuff before. If you are not familiar with that stuff, I'd definitely recommend that you roughout the design you are looking for and the features you want. Make the floor plans/layout you desire, including placement of heating equipment, plumbing etc. Then take this to a qualified architect or timberframe shop with the engineering capabilities. Ultimately the person you work with will likely make recommendations for certain changes to improve your layout. Those who do this all the time have way more experience and can often suggest significant improvements. It is worth the money to work with an experienced engineer or designer or architect. They will often (should) save you money. You should work with some one who can do the necessary timberframe calculations to size beams, joints, and determine number and size of pegs. Even though I am a mechanical engineer, I will work with someone with more experience designing timberframe homes to suggest improvements. I will do all calculations myself, but I will also have another engineer do it too in order to check my work and assure things are correct.
