You’ll need to shrink your trimmed surfaces. There are no native grasshopper components for this. I used a simple script from here:
There are also plug-ins that have components for this (Pufferfish, Sasquatch, Wombat, etc…)
Roofing_221126_re.gh (16.7 KB)
I’ve deleted everything except the portion of your file that pertains to your question.
-Kevin