Once you have a towel under the door roll another towel up and place it in front of a closed door as you would a draft excluder.
Rats crawl under garage doors.
At least for your door you can start with using a door sweep stop.
Look for damages on the garage door.
You ll have to fight it.
These are essentially a metal mesh that reinforces the barrier between your garage and rats.
Rats can easily chew through that.
Yes you can use a towel under a door to stop mice but you will need to squeeze it underneath and double up with the towels.
Install one that is made of metal instead of vinyl.
No place in your home especially a crawlspace is safe from them.
Mice and rats can be a tricky animal to get rid of especially in a home.
These come in various shapes and are sold are your nearest home depot in the hardware department.
Their droppings can also cause serious health problems in humans and other animals.
Rats will also eat and contaminate your food.
They are thin metal and can be bent around the vinyl.
Start with one and try to get as much of the towel under the door as you can.
If your garage door has a rubber seal check it regularly.
In the infestation is already present there s nothing you can do about the previously mentioned points.
I picked up a set of these garage door rodent guard strips off of amazon and used them to reinforce the vinyl weather stripping on each side of my garage doors.
Stop rats from getting in garage doors.