I only imagine having at most 3 horses, but the new barn will have 5 stalls. I am designing a place that will appeal someday to horse people when the property is sold (after I kick the bucket).............
I read about having 10X10 for each horse! That would be 50ft long! Ugh TOO BIG!
My purpose would be just a place for the horses to get out of the wind, sun, or weather for short duration, as the need arises!
My "philosophy" from what I've read is to keep the horses in pasture (I have 9 acres with three paddocks) as much as possible. Yet keep the barn seperate from the pasture.