gazumping

I figured it out with your help. At first I couldn't see all the changes but after a detailed comparison I learned that the locations of each of those roof and wall elements must be in exact locations for the "cut" feature to work properly. Chalk it up to a minute set of misalignments on my part. TL;DR for anyone else: make sure your walls and roof planes are properly lined up - exactly. Thanks again for the lesson.

Yes, that's it. Very much appreciated! May I ask what the key changes were?

Glenn, Yes, overall that looks like it with the exception that there is now a floor over the open area but the opening between the two pitches looks right! Apologies also, I did not add a signature with my version which is version X10 Premier so I can't unfortunately open your plan file you sent.

Hello everyone, I use X10 and was trying to experiment with a 1.5 story cabin with open ceilings and have two different pitches on the roof, 8" in the back (for the upstairs) and mid way through go to a 12" pitch for a cathedral ceiling. I can get almost everything to work but I can't hide/remove the interior part of the wall where the two pitches meet. The back of the house is effectively a pair of large shed dormers that extend to the back wall. If there is a way to connect a dormer edge to that back wall then that would work as well. I am including a sample plan that when viewed from the inside shows two walls on each side of the 2nd floor - those are the ones I'd like to remove yet retain the exterior wall that connect the two different pitches. And now that I see the image the upper attic wall should also be removed. Any guidance on how to remove those interior walls or a better method of building such a structure would be greatly appreciated. --Christian 1.5-dormer.plan