How do I get rid of stray light cracks?

HI I have this common problem, when I’m putting rooms together and even though their is not cracks in between two meshes. It still let through light like this:

Any idea how I can prevent this?

Hi!

I guess what’s happening here is that you have a low res lightmap assigned to the mesh(es) or your lightmap uvs are not laid properly and basically the lighting information from the other side of your mesh is pulled over to this side… if you’d check the lightmap density view I think you’ll see that the line of texels are not properly lined up with the edge of your wall…

Or you can just put something in the way, outside ( really depends on what’s out there… )