My first Scratch Build.

[ocalicreek]

Just had an idea. Make a rectangle as high as the roof (from the top of the walls to the peak) and as long as the distance from one corner to the other (including overhang). Now mark the mid-point along the top (where the peak will be) and connect it with lines to each of the lower corners. Cut the small triangles on either side off. The large triangle will be one axis and the smaller ones, inverted of course and set perpendicular to the large one on either side will be the other axis. Just measure to make sure the cutting didn't remove too much or too little material on one side or the other. Capiche?

Galen