Types of sheetrock available and their uses. The most common type of sheetrock used is 1/2″ because it can be used in most areas of residential construction. You should definitely check the codes in your area because waterproof rock will be used in wet areas and 5/8″ rock will be used anywhere fire rating is required (typically in garages, furnace closets, and between separate living units). The new lightweight sheetrock is an incredible plus, I’ve seen no downside to using it in place of the other. The waterproof rock is required in some situations but remember that no rock can be wet for long periods of time, it will all deteriorate with time.