Im going to install a ceiling fan box but am unsure on the type. Its a new construction house, so its pre drywall. My question is, its a vaulted ceiling and I am putting the box on the peak. I looking to use a special box that is to be used for this but I dont know the right size. I was told the pitch is 9.5 whatever that means. I would go see for myself but the house is 400 miles away.