Since drywall installation is common practice, knowing the differences between the main fire-rated products is imperative. Let’s point out one main thing: due to the water composition in gypsum, all drywall types retard the spread of fire to a degree. But type X and type C drywall are both specifically designed to resist fire and thus increase safety. So should you just pick either off the shelf? No. There are differences between the two products. And even if you plan to hire a drywall contractor for the job, it’s vital to know the basic distinctions. Here we are going to draw the line between type x and c drywall to help you understand the differences.

Main characteristics of type X drywall

Type X drywall is 5/8 inches thick and the first fire code product. It contains gypsum with noncombustible glass fibers, which increase the fire rating 1 hour minimum.

Please note that there is a type X Shaftliner drywall type with even greater fire rating qualities but this one is installed in shaft walls, stairwell enclosures, and area separation firewalls.

Main characteristics of type C drywall

Type C drywall is the improved version of the x type. This fire-rated drywall type is available in 1/2” and 5/8” thicknesses and its gypsum core still consists of glass fibers. The difference with this type of drywall is that it contains more glass fibers than its x type counterpart and also additional vermiculite components. These extra qualities make it even more resistant to fire since it will slow its spread by 2-4 hours.

Fire-rated drywall test drive

Tested by AWCI (the association of the wall and ceiling industry) in the same conditions where fire rated drywall types were exposed to the same heat, they reacted as expected. Standard drywall types managed to retard the spread of fire for 12 minutes before the board cracked. As for out two contestants, type X kept strong for 57 minutes before it started cracking whereas type C lasted for a little over two hours without failing at the end.

The differences between types X and C drywall

This test proves that type c drywall is the best fire resistant product in the industry since it holds twice as well as type x and ten times better than the standard drywall. The question though is whether the test shows that it’s better for us to use type c drywall instead of the other types. Well, not always. The test might show the strengths of each drywall type but you need to remember two things:

• Drywall companies install fire rated boards around boilers and on walls separating the garage and the house. That’s because the fire rated boards are more expensive than the standard ones and the rest of the structure and things inside the house are not always fire resistant either.
• There are differences between the type x and type c drywall. Although the type c drywall comes in thinner boards and that makes installation easier to drywall contractors, this type of board is not recommended for all applications.

Type C drywall is only 10% more expensive than type X drywall. Yet, the two types shouldn’t be used interchangeably. One of the most important distinctions between the two fire-rated drywall types is that type C performs better when it is installed horizontally. And thus it makes a great option as a ceiling drywall but won’t offer the same fire rating if installed vertically.

The good news is that fire-resistant drywall hits the market once it is certified by a third party. And the even better news is that the designations of UL point out the best applications of each drywall type. So it’s best to turn to a drywall company that will know these things to be sure the main structures of your home are fire-resistive.