Need To Know How To Figure The Pitch Of The Roof Of A Barn I'm Building?

The pitch is the ratio of the rise to the run.  A 6:12 roof rises 6-feet for each 12-feet of horizontal distance.

If you have a 40-foot wide barn and you want a simple roof, the rafters would be 40-feet wide.  Each half would rise 6-feet for every 12-feet of width.  There would be 20-feet from the edge to the middle so the peak would be 10-feet  above the wall.

Other pitches are possible.

Some barns have two slopes - a steep part  (12:12) on the bottom and a not so steep part on top (4:12).  This allows a large loft without letting the roof get wayyyy high up in the sky.

So, what's your question?

Angles for pitch

This is a rather interesting question, I accidentally found your topic and if you are still looking for an answer to your question, then I think that I can help you. I already had some experience with roof repair, so I can give you a couple of tips. For the start naturally, you need to find good builders, except if you want to build your barn with your own hands. With your plan you can also use the the roof pitch calculator. Here is url. Try it, experiment with it. I am sure this should simplify your task. Plus, if you have any problems, do not worry, this is normal, I advise you to consult with professional builders on this issue too