Sky visible through stairway hole in 2 level house
Fellow modellers, looking for a tip in order to solve the following issue I have with stairs. My model is more complex but for simplicity, I tested and recreated the issue on simple, rectangular, two stories house, consisting of just a single room with stairs. Looking from ground level up, towards the stairs, one can see the sky instead of a second's level walls. Looking down from level 1, everything works correctly. Experimenting the whole day, still no idea what am I missing?
