This is one of the smaller DPM n-scale structures. I have built the kit basically per the instructions two times.
Once was when I had Tobias Locomotive Works details for it; including the roof. My assembled versions had an exterior foot print of 17.5 X 36 scale feet.
Several years have passed since I built the two. I decided to use the kit as a starting point for a single story structure yesterday. I measured, scored and filed the four wall section to achieve the desired front, side and back elevations.
It had gone very smoothly up to this point, so I started the gluing step. It was then that I discovered that if the back wall is used as is, the resulting width is 19.5 scale feet.
"Okay," you say, "what is the big deal about 2 n-scale feet."
"Well," I will tell you, " the front wall width is only 17.5 n-scale feet, thus not yielding a rectangle."
I forgot that I sanded 2 scale feet off the width of the two kits I assembled previous.
Back to the drawing board. Or to paraphrase the old carpenter's adage, "measure twice and then glue once."