Pro Tip: Unless you’re matching existing drywall, there’s rarely a good reason to use 3/8-in. drywall. Remember that window and doorjambs are generally sized to be flush with 1/2-in. drywall.

You can have one layer on each side of the stud and still have a 1-hour rating, as long as you’re using a fire-rated gypsum board (aka drywall) like Type X, along with batt insulation. Plain gypsum ...