Fire Rating Of Durock Vs. Drywall

Fire protection within a structure is one of the most important issues faced during the construction or design of a building. While certain installations must be built to a standard code as specified by local or statewide officials, some materials are put in use by the preference of the builder or designer. Such materials include drywall, also known as Sheetrock, and Durock, also known as cement board.

Durock is manufactured in sheets with a thickness of anywhere from 1/4 to 5/8 inch, a width of 32, 36 or 38 inches and a length between 4 and 10 feet. The exact fire rating of Durock is dependent on the other materials used during construction, but a panel 1/4 or 1/2 inch thick typically provides an additional hour of fire protection. A Durock panel with a thickness of 1/2 or 5/8 inch can provide two hours of fire protection when installed correctly and in conjunction with all fireproofing construction materials.

Standard drywall, manufactured in sheets with a thickness of 1/2 inch, provides only a minimum 30 minutes of fire protection. Commonly seen in lengths ranging up to 16 feet, standard drywall is used in most residential applications.

Type X is a designation that is given to sheets of drywall that are manufactured using glass fibers and other noncombustible materials for added fire protection. Sometimes referred to as fireboard, Type X drywall is available in two thicknesses: 1/2 or 5/8 inch. Because of the added weight of the extra materials used during the manufacturing process, Type X board is usually limited to a length of 12 feet. Respectively, these provide an additional 45 minutes to one hour of fire protection.

Standard drywall up to 1/2 inch in thickness is commonly used for interior walls in residential construction. Sheets that are 5/8 inch thick, which are widely used in commercial installations, are sometimes used on ceilings and walls in residential structures. Type X or fireboard is typically used on walls that join separate housing units; walls between a house and a garage; and around furnaces, heaters or fireplaces. It also sees use in commercial shops, factories and even retail stores. Durock's most common residential usage is in swimming pools and shower stalls, though it is also used in factories and shops where high heat or open flame is a concern.