I don't think more light is necessary, Delphian. It would completely destroy the mood.
Gotta say, I love the chair in the last shot. Little detail that really adds to the atmosphere - whoever was in here really needed to keep someone out, running out of wood to bar up the windows, so used the chair. Don't know if that was supposed to be kind of comical, but it's also deeply disturbing on another level.
I can't see the lighting glitch in the last shot, but in the first shot, it does appear that some of the arms are coming out of the wood, rather than between the planks. Also, some of them seem to be coming through the window at far too high a position. Unless these are mutant zombies with massive legs, or something else entirely is going on behind those wooden planks...
The texturing on the walls seems kind of bland as well. I think it's that it doesn't seem un-maintained enough, if you get what I'm saying. The walls should have the wallpaper (if that's what it is) all ripped, peeling and mouldy. The floor should perhaps be all covered with debris - leaves blown in, maybe a yellowing (bloodstained?) newspaper discarded on the floor. I don't know, it's just all too neat? Tidy? Something like that. The room in the last shot exudes that feeling of something gone horribly wrong in this house, but apart from the arms, that first room just ... doesn't.
Likewise for the stairs... the walls and bannister look in far too good condition to my mind.