dthornton

I have an 1890 two story that I'm remodeling. The studs are "shotgun", that is they go from the foundation to the attic (no insulation). We have plaster and lath pulled off of walls in a couple of rooms. We've had bats come in and fly around in the house several evenings. I've caught several and turned them loose outside. I know that I need to seal up every hole in the house to prevent them coming in, but that will be a long process. Does anyone know how to discourage them from setting up housekeeping in my house? I don't want to harm them (did you know that a bat will eat it's own weight in mosquitoes every night? ). I just don't want to share my house with them! My wife totally freaks at then flying around inside!

nealtw

They do a good job, but you don't want to share your home with them. Screening over soffet and other vents would help.
While you have walls open, put solid blocking in the walls at the floor and ceiling, you don't want airflow from the basement to the attic. It's called firestopping.

Dionysia

I know your question is about bats, but here goes.

We just had an engineer look at our balloon-framed 2 story house. We don't have the written report yet, but he did tell us that in most of these old houses the lathe and plaster served a structural purpose to keep the studs from moving. [Our lathe and plaster was long gone when we bought the house] Also, people back then didn't have as much junk as we do now, so often the old framing is inadequate for the loads our modern lifestyles create.

Our house at one time had a fire in the basement that traveled through the wall bay to scorch the skip board on the roof 40 feet above. As long as the bays are accessible, installing fire blocks is a really really good idea. Blocking any available holes will not only keep bats out, but will help with your heating/cooling costs as well. Our problem isn't bats - it's wasps, but the same principles apply. Replacing rotted wood and caulking small openings is tedious, but necessary if you want to live a bat-free life. Also keeping your screens tightly affixed and in good repair in your gable vents is an often overlooked but simple solution.

joecaption

Google "bat house".
It may help to provide them some alterative housing on the property.
I've tacked up strips of Tyvek between the wall studs once the blocking in place. It cuts down on the air coming in between the wood siding but still allows the wall to breathe.
They only need a tiny hole to get in, just a loose piece of siding could be enough to let them in.