The thickest residential drywall typically available is 5/8 inch (approximately 16 mm). This type of drywall is often used in areas where increased fire resistance, soundproofing, or greater durability is required. It is commonly used for ceilings, walls in shared living spaces, and where building codes or specifications demand a higher level of protection. Thicker drywall can also be used to provide a better surface for attaching heavy objects, such as cabinets or bookshelves, to the wall.
In contrast, the standard thickness for residential drywall used in most interior walls is typically 1/2 inch (approximately 12 mm). This thickness is sufficient for most residential applications and offers a good balance of cost-effectiveness, ease of installation, and reasonable durability.