Doggie doors?

my 3 cats are mostly outside cats. They rarely stay inside the garage when it is cool.
I have an outside shed and I am thinking of adding a doggie door so they can go in there when it rains. We don't have a roof in the backyard.
Do you think that the door would work?
Thanks
Angie

Yeah, I don't see why not It would allow them to go outside/inside as they wish... I personally don't let my animals outside, so I don't have experience with this at all. But, I'm sure someone that's done this before will come along and give you good advice

The only thing you have to be careful of is predators that can follow them, fit through as well, fox, dogs....... It is a good idea for them to have an indoor shelter access always though!