Faces who's not affected by light, and light penetrating walls.

Ok, ive had this problem for a while, some faces are not affected by light, but instead, there just all black…

Is there something ive missed?

Here’s a screenshot:


Your normals are facing the wrong way.

Either flip them (select the face in editmode and hit w–flip normal) or recalculate them (Ctrl-N or Ctrl-Shift-N)


Oh my god, thanks, your a life saver!
After all this time, ive never known that…

I have another question, how do i stop the lights from one side of a wall, to lit up things on the other side of the wall?

screenshot example: