Building codes require fire-rated Sheetrock on the walls between an attached garage and the remainder of the home, and around the boiler in multifamily dwellings. This building material is slightly thicker than regular drywall and increases the wall's fire rating to a minimum of one hour.
Contractors may refer to fire-rated drywall as Type X. It doubles the fire rating of a wall by using a core that is also denser than typical drywall and includes glass fibers that prevent crumbling of the gypsum upon the exposure to high temperatures. It is slightly more expensive than normal drywall, as of 2016. The actual ability of a wall in preventing the spread of a fire may vary greatly from the tests laboratories use in certifying fire-rated materials.