Mounting a pet door on a garage door can be a convenient way to give pets their own entrance. Though, whether it will work or not depends on the garage door.
The pet door frame can’t be taller than the garage door panel height, or it will interfere with the garage door as it opens and closes.
As an example, the PlexiDor medium dog door frame measures 13 3/4″ wide by 15 1/4″ high from frame edge to frame edge. The garage door panel would have to be at least 15 1/2″ tall to be able to accommodate the pet door.
Also, look at the back of the garage door panel and make sure there isn’t something there that will cause problems when cutting a hole for the pet door.
The pet door frame is 1 3/4″ thick. This means, the pet door needs to be screwed to the outside surface of the garage panel door – it must be flush with the garage door surface. On the inside, the pet door frame will stick out about an inch or so.