Light Peeking Through the Seams of my Building Mesh

I modeled my own building, exported it as an FBX and imported it into Unity. Everything seemed to transfer over, except that little dots of my Directional Light are coming through the mesh.

The roof of my building looks like this:

I designed the ceiling to match. They are their own separate meshes since Unity only renders one side:

On the floor below, I can see small specks of light that seem to be peeking through the seams where the polygons on the mesh come together:

Are there ways in Unity to fix this? Maybe I could change a setting on my directional light, or add a component to the building object so that it is more restrictive on how it lets light pass through?

Look at the bias and normal bias in the directional light. If that doesn’t work you indeed have to add some additional geometry to add shadows.