Husband wants to enclose the back porch

I am in a running battle with my ADHD husband about the back porch. He wants to enclose it as an office. He knows NOTHING about building construction, but yet INSISTS he can do this. I have put my foot down and said ABSOLUTELY NOT because of the permits, the building codes and knowing FULL WELL what it's going to look like when he gets "done" with it.

     There are already at least 2 dozen projects around the house that have yet to be completed, and they have been staring us in the face for years now. I CAN'T HANDLE ANOTHER UNDONE PROJECT....ESPECIALLY A GREAT BIG ONE.

     1. The broken hot tub....that he broke while trying to get it winter ready, so that the cold weather wouldn't "break" the tubes, so HE broke it. He now won't go under it because of the dreaded "spiders".

     2. The house is about one third painted, inside and out, so the house is in different colors.

     3. The yard NEVER gets finished, so I am the one left doing it, while he is yelling at me to NOT do it. (I have a severe back problem) It ALWAYS looks a mess.

     5. He's broken both sets of sliding doors in the house, and the doors are in the garage, so the closets and the washer and dryer are open to the world.

     6. The garage is filled with his "tools" always dirty and a mess, unless my daughter and I clean them up.

     7. The gutters NEVER get cleaned, and I can't do it. Causes a problem with runoff around the house.

     8. Broke the kitchen sink while trying to install a water filter.

     9. Installed a new dishwasher (against my wishes) and now it "floats" around the kitchen instead of being locked in it's place under the counter, when I begged him to call a plumber.

10. Built a "patio" outside with tiles, but are all crooked and now a mess. It cost about 3 times more than cement would have cost, and it has to totally be redone now.

     This is just ten items right off the bat, but there are many more. HOW CAN I CONVINCE HIM THAT A PROFESSIONAL HAS TO DO THIS ENCLOSURE? He won't listen to me when I tell him I can't take one more undone project.