Drywall can be classified in different types. These types reflect the nature and modifications done on the drywall. Among the major categories are traditional drywall, moisture resistant drywall, eco-friendly drywall, soundproofing drywall and fire resistant drywall. Sometimes drywall in one category can serve purposes of the other categories. This is certainly the case with fire resistant drywall which aside from its specific role, its nature allows it to have great sound proofing abilities.
The makeup of drywall makes it a natural fire resistant material. This is because it consists of 21% water. During a fire this water is released as steam and in the process it slows down the transfer of heat and thus fire to the other side of the wall. The problem with regular drywall is that after sometimes it crumbles and fire gets to spread. This is where fire rated drywall comes in. Fire rated drywall comes with more proofing including fiberglass and other additives which increase its ability to withstand fire longer than regular drywall.
A standard 1/2’ drywall can offer up to half an hour of fire resistance. It is used in most common areas of the house because it has a lower cost.
The real fire rated drywall has to be certified by a third party. This is usually an independent testing and listing company to confirm it meets the fire performance requirements as set down in regulation. The most common fire rated drywall is referred to as type X. It is 5/8 inches thick and is installed on each side of 2 by 4 inch wood studs spaced 16 inches. In the case of steel the studs are 3.5 by 8 inches and spaced at 24”o.c. Type X drywall has a minimum fire rating of one hour which is the requirement for many building codes. At home the drywall is usually placed between the garage and the rest of the home.
This is because the garage, with the combustible materials and chemicals often stored there, is an area where fires are likely to happen. The type X can also be used in other high risk areas depending on your budget.
Aside from type X there is type C fire rated drywall which is an improvement on the type X. It is available in 1/2-inch and 5/8-inch thicknesses. While constructed in the same manner as type X, type C makes use of more fiber glass and other components added to the gypsum core which increases its fire resistant qualities. Next is the Type X Shaftliner which has even greater fire resistant qualities. It is one inch thick and is used in shaft walls and area separation firewall assemblies.
The idea behind fire rated drywalls is to provide time for people in a building to safely exit them during a fire and make it to the fire assembly point. It is thus a requirement by many building codes for the fire rated drywall to be used especially in high risk rooms. The fire rated drywall is costly and the higher the resistance time the higher the cost. The more specialized designs are available with special order.