When you are installing drywall, often building code dictates certain types of drywall that must be used. One type of drywall that shows up in building code is fire rated drywall, also known as Type X drywall.
While beneficial, fire-rated drywall is often given more attributes that it has: it is fire-rated, not fireproof; it is only one of many methods homeowners should use to retard fire; and testing procedures are deemed imperfect (at least by one drywall manufacturer).
- Thickness: 5/8"
- What Makes It Fire-Rated: Glass fibers are added. Also, because it is denser than normal gypsum-and-paper drywall, it takes longer for fire to degrade it.
- How Long It Lasts: Up to 1 hour fire rating.
- Other Names: Also called Type X drywall.
- Other Benefits: Type X absorbs sound well.
Fire-Rated, Not Fireproof
Type X is by no means 100% fireproof; simply it is drywall that will stand up against flame longer than regular drywall.
Also, just because an area is rocked in Type X does not ensure fire safety. Fire can still find other avenues to travel: vents, doors, gaps, etc.
If a conventional 1/2" thick sheet of drywall will stand up to 30 minutes of fire, then the added 1/8" found in the Type X drywall, along with its other properties, will increase your margin of safety another 30 minutes.
For this reason, fire-rated drywall is sometimes called one hour fire wallboard.
Places to Install Type X Drywall
In residences, fire rated drywall is typically required by building codes to be installed in a few of these places:
- Near furnace and utility rooms.
- Places where a wood stove is used
- Garages and/or the garage walls that separates that area from the main house
- Garage ceilings that have living areas above
Why Not Use Type X Everywhere?
Fire rated drywall tends to run about $2 more expensive than conventional 4' x 8' panels. While this is not much in the small scale, it can represent a substantial cost difference when multiplied across an entire home's worth of drywall.
More importantly, fire will find any number of easier passages to travel than through drywall, when installed in areas other than those listed above.
In other words, if a bathroom, nursery, bedroom, or home office were hung with Type X, fire would readily move through oxygen-rich open doors and hollow-core doors long before attempting to burn through the drywall.
If you want fire rated drywall to be installed all throughout your house, you would need to request this with the contractor, as this is not normally done.
The ability of Type X to withstand fire is tenuous and not fully understood, at least according to one major manufacturer of fire-rated drywall, USG (Brand: Sheetrock® Brand Firecode® C Gypsum Panels).
USG makes the point that ASTM (American Society For Testing and Materials) testing of fire-rated drywall requires that entire "assembly/systems" be tested, not just the drywall.
Because these assemblies are composed of many different parts, any of which could affect results, these results may be skewed.
This simply means that for a "one-hour fire rating" of a gypsum board assembly/system, all requirements of an ASTM E 119 test were successfully met in a testing laboratory furnace for at least 59 minutes and 30 seconds for that specific assembly/system and with those specific components of the assembly/system.
Drywall typically comes in 1/4", 3/8", and 1/2" thicknesses. But Type X drywall is 5/8" thick. In addition to the usual gypsum found in regular drywall, fire rated drywall contains glass fibers to form a super-tough core. Not only that, the gypsum and fiberglass are packed in tighter and denser than in regular drywall.
Cost and Availability
Fire rated drywall costs more than the regular drywall. As a rule of thumb, you can count on it costing about 5% to 7% more than conventional drywall of the same thickness.
Type X is not a specialty product; it is available at local home improvement stores or contractors' supply houses.
Two added benefits to Type X drywall: it inhibits sound transmission and it stands up well to impact.