Boolean difference issue

Originally when I baked the image from GH there was an issue with boolean differencing it because there were multiple polysurfaces that composed the “massing’s” I wanted to alter. I fixed that issue and when I began trying to remove from my object with polysurfaces that are suppose to encompass it, it seems to fail. I looked up possible issues and I’ve made sure they were closed surfaces. It allows for the command to work when dealing with horizontal differencing. However, I am trying to remove the excess that wouldn’t be visible in the vertical orientation. I’ve ungrouped them to try each individual vertical louver to no prevail. Any ideas on to why it works with other objects, but failed with this one?

Boolean Difference Issue.3dm (6.5 MB)

The object I am trying to remove from is the center component that is suppose to be held by the two tower like massing’s on both sides for clarification.

I don’t understand much about the object you need but besided the order, the problem is in the inner surfaces of the big objects:

if you rebuild the selected surfaces, it works ok :

My issue was not exactly hollowing the center of the object, but rather removing overlapping portions that overlap with the two vertical masses. I could be misunderstanding your suggestion.

try rebuildding those surfaces, then make the operation you need. if it works in one direction should work in the opposite. the intersection is the same.

Alright, I will try that now and let you know if that solves my issue. Thanks for the suggestion

At first I was getting the same error message, but then I tried a different surface and it worked. I’m still unsure as to why that happens, but I appreciate your suggestion as it did solve my issue. Thank you.

yes it’s weird. I didn’t find any issue on the surfaces. it was trial and error haha

Haha I still appreciate you taking a look at it.