Instead of letting you pet scratch the door when he has to go out teach him to ring the bell. After he rings the bell praise him and let him go out to do his business. Place gotta go door bell on your door knob.
Simply hang gotta go over a door knob that leads outside, and hold your dog's paw and teach your dog to ring the bells
When the bells ring, praise your dog, open the door and tell the dog to go outside
When the dog relieves themselves, open the door and praise your dog again
Repeat these steps several times a day. It is a pleasant alternative to door scratching or barking