This is our first go @ chickens & we have six 4 week old hens [i hope]. i built a 12x6 run with an elevated platform & 2 nest boxes... obviously, they won't need the nests for a while, but, i'd like to be able to leave them in there @ night with a heat lamp. we put them in today for the first 'run around' & now i'd hate to put them back in their little box. we live in North San Diego - so it doesn't get too cold @ night, but i think the lamp will help. anyway... i still have a few gaps in the coop. at the very top where the soffits will go, they are open 8" x 24" i doubt they can get up that high & get out, but, i'm wondering what might get in? & under the door there is a 1" gap - mice maybe? should this coop be fortress tight? or am i over thinking it? Oh, & i have the bottom of the coop sealed off with chkn wire too.