I just purchased a new fiberglass back door and had it installed. I also purchased a pet door and had that installed in the back door. A couple of weeks into the pet door experience, I came to determine that the pet door we ordered isn't working and now need to exchange it for a different model pet door.
The rough cut for the replacement pet door is going to be 5 inches shorter in height than the current pet door. There will be a 5 x 11 space in the middle of the door that needs to be filled.
I'm thinking of using a sized piece of metal, like aluminum, filled with some Great Stuff or something similar. The part I'm looking for feedback on is what to use to fill the small lines of gap space between filler material and the door. Would silicone be good for that or is there something else that would be better for smoothing out those lines? I'm really hoping it's possible to have this hole not be detectable once the doors are exchanged.