The bottom line is that this is very detail-oriented work. Experience matters, and I do highly recommend calling a professional who has done many bat jobs to expertly and properly seal the whole structure against any bat entry.
Customer Bat Email: Hi, my mother sent me a link to your blog because I have bats! I think your blog and all your photos are great. We live in Canada though. In the interior of British Columbia. We have tried everything to get rid of the bats. Hanging netting off the roof (it gets blown off), moth balls 9I understand the exact concentration to rid the attic of bats is at a rate toxic to humans!), lights, loud noises, and a favorite - smudging a can of dried cow manure. This actually really worked the first two times we did it. After that, the bats just ignored it. Oh yeah, we have tried burning insect coils and actually spraying insecticide directly on the bats (I hate that one - and I don't think it works anyway.) The bats leave in the winter, but every spring and summer they are back. We live in a log house, with a tin roof. Any suggestions? We have two small bat houses away from the house, but I have read about a really big bat house project (I think in Mississippi) big enough to house around 1000 bats and have thought of this to try to attract them away from the house. I, like you, like the bats, but not in the house. We have cats that catch them if they can and they do get into our bedroom on occasion which is always lots of fun. I can't imagine having an eradication team out here every year, but we have to do something! Can you give any suggestions? Brenda
My Response: Well, of course you need to seal up the house so that no bats can get in again! You don't need a "bat eradication team" out every year. Just seal the house up properly once, and your problem is forever solved! You have to use sealant and seal shut every last gap and opening and nook and cranny - it'll also help insulate against those balmy Canadian winters! Oh, and please don't spray insecticide on bats. They are good animals. Wait until the bats leave this winter, be sure that none are hibernating in the attic, and get to sealing!