The trim i ve used and seen it happen on is the fine thatch roof trim.
Sims 4 roof trim glitch.
It commonly occurs when people use fencing or half walls in the interior that connect with an exterior wall it can also happen when building with manual walls vs.
By default roof pieces have straight pieces of roof that continue from the top of the roof to the outer edge in a straight line at an angle that is determined by the height of the roof.
This is not actually a bug but a matter of how the space is constructed.
Lansta1 friezes and trims can intrude into the interior when the interior or part of it is not what the game considers a room.
Sections of roof trim will just be black.
Songofawesome i have tried adding roofing sections of two types on three different floors and added the both of the version of the roof trim and cannot reproduce the issue these tests also included medium and regular wall height floors.
Here are a few tips to help you graduate beyond just making a box with windows.
Also adjusting the the height of these roofs does not seem to effect whether the shadow is there.
2 22 2020 here s a screenshot of my house having this issue on the current patch.
If i add a roof to the front room it makes no difference.
This is happening on ps4 also with 1 20.
If i move the roof that was on the room i just deleted down to be on top of the middle 2nd floor room the shadow appears against that roof section.
I have a screen i will post when i get a chance.
We can alter this however by grabbing the bow tool which appears as a ball when we select a roof piece.