How to hide parts of mesh?

Hello folks, I want to hide part of my building in realtime. I’m currently using transparent shader as my mask to do that (based on this answer). However, depending on the camera angle parts of the mesh I didn’t want to be hidden are being culled out.

I want something like the building being cut horizontally and the upper part is hidden and the down part is shown

Sorry, I don’t have much experience in shaders, that’s why I am asking.

For those looking for a solution, I found this article very helpful. The approach is by using a clipping plane to cut parts of your mesh based on the y position of this plane

I see no one has offered you a solution.
But by now you must have found one yourself.
To anyone that’s googled this, a video explaining masking in Unity is available on YouTube.