Recently, I had part of the ceiling out in my basement bathroom. I noticed when I removed some insulation to run a 4" exhaust fan duct through the rim joist to outside that there is a 1 - 1.5" gap between my concrete block and the exterior brick. Does this sound right? I'm wondering cause I found a bunch of dead bugs, an acorn, and a big bee's nest between to floor joists near this gap. Should'nt there be something there to seal off this area?