Sheetrock fire rating: Type X vs. Type C Drywall

Type X vs. Type C Drywall

During the housing and baby boom following WW2, drywall became a staple on construction sites of all types. Rather than the painstaking process of nailing wood or metal lathe to framing and covering it with plaster, drywall was a faster option that requires less skill to hang. There are now several types of drywall, including standard, mold-resistant, and soundproof, to name a few. Another variant—popular for its ability to save life and property—is fire-rated drywall. This guide on fire-rated drywall and how it works will help explain it all.

All drywall is fire-resistant. A sheet of drywall has a gypsum core, which is a non-combustible material made from calcium sulfate dihydrate and water. Fire-rated drywall takes this a step further by adding in other non-combustible materials like glass fibers and minerals.

Understand that the drywall’s fire rating isn’t necessarily for the individual sheets of drywall. It’s rated for an approved wall system, including the studs, hardware, and installation methods.

Type X drywall is basic fire-rated drywall. It contains the same gypsum material as standard drywall, with the glass fibers added in for structural integrity during extreme heat conditions. It’s often used between garages and living spaces adjoining and above the garage.

Type X rated drywall comes in sheets 48-inches wide and in lengths up to 16-feet long, and it’s usually ⅝-inch thick. The added 1/8th inch and glass do make this much heavier than standard drywall, but layers of two sheets of drywall totaling 1 ¼-inches thick give the wall system a fire rating of up to 2 hours.

If the Type X drywall is the basic model, Type C is the new and improved version with additional fire-resistant materials. When this material is exposed to extreme heat, the water contained within the gypsum core becomes steam and dissipates. However, instead of immediately shrinking, Type C drywall contains vermiculite, and this mineral expands under extreme heat, filling the space left by the evaporating water.

Type C fire-rated drywall comes in standard sizes like Type X drywall, but it’s also available in ½-inch thicknesses to make it more manageable. It also lasts longer than Type X drywall, with a single sheet lasting as long as 2 hours.

Note: Type C is not universally accepted by local building codes the way Type X is. Builders should check with local fire code officers to ensure that Type C is acceptable, and to determine which thickness the project requires.

Regular drywall is non-combustible, but it’s not impenetrable. As the heat intensifies and the drywall heats up, the water in the gypsum core releases in the form of steam. This causes the drywall to shrink and eventually crumble. This process can take up to 30 minutes, meaning even standard drywall can help resist the spread of fire and gives the home’s occupants time to escape.

What is fire-rated drywall?

Type X drywall

Type C drywall

How does fire-rated drywall work?

Type X and Type C drywall have glass fibers and vermiculite (depending on the type) added to the gypsum core, which helps to slow the crumbling process further. Besides just paper and gypsum, these glass fibers and minerals reinforce the structure of the drywall. While heat still affects the drywall, it’s less likely to crumble as quickly, allowing it to stay intact for up to two hours, depending on the type.

Once the drywall panels crumble, however, the fire will spread through the wall. Also, note that fire-resistant drywall will contain a fire to a space, but if there are open doors or non-fire-rated openings such as doors or pass-throughs, the fire will easily spread to other spaces.

Where is fire-rated drywall required?

Building code may call for fire-rated drywall in specific places. These are generally areas of the home where high-heat conditions are more likely to occur, as well as where the possibility of actual combustion is higher. They include:

Areas around furnaces, boilers, and utility rooms
Attached garages between the garage and the living spaces
Rooms with wood-burning stoves and appliances
Commercial buildings like apartments, condos, hospitals, and office buildings

It’s possible to hang an entire home’s interior with fire-rated drywall, but since it usually costs about 10 to 20 percent more than standard drywall, this can be very expensive.

Conclusion

Fire-rated drywall is more expensive and heavier than standard drywall, it’s true. However, it’s well worth the investment in some spaces, and it’s even a requirement in certain situations. Be sure to find out where fire-resistant drywall is required in your project as well as which type meets local codes. This building material could be the difference between containing a fire to one room or a home being a total loss, so be sure to use it where and how it’s required.

MT Copeland offers video-based online classes that give you a foundation in construction fundamentals with real-world applications, like drywall finishing. Classes include professionally produced videos taught by practicing craftspeople, and supplementary downloads like quizzes, blueprints, and other materials to help you master the skills.

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Types and Uses of Fire rated Drywall

HOW TO CHOOSE A WET DRY VACUUM

How Many Drywall Types Are Out There and Is All Drywall Fire Rated?

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 drywall fire rating. 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 type x drywall fire rating 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.

How do You Know if Drywall is Fire Rating?

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 to ensure fire protection. The most common drywall considered to be fire rating 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 drywall 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.

Drywall combustibility group

Flammability group is a conditional characteristic of a certain material that reflects its ability to burn. With regard to drywall, it is determined by conducting a special test for combustibility, the conditions of which are regulated by GOST 3024-94. This test is also carried out in relation to other finishing materials, and according to the results of how the material behaves on the test bench, it is assigned one of three flammability groups: G1, G2, G3 or G4.

Content of the article:

Is drywall combustible or non-combustible?
Drywall combustibility group
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Video
Fire hazard class

Drywall combustible or non-combustible?

All building materials are divided into two main groups: non-combustible (NG) and combustible (G). To get to the non-combustible, the material must meet a number of requirements that are imposed on it during the testing process. A drywall sheet is placed in an oven heated to a temperature of about 750 ° C and kept there for 30 minutes. During this time, the sample is monitored and a number of parameters are recorded. Non-combustible material must:

increase the oven temperature by no more than 50 °C
produce a sustained flame for no more than 10 s
will decrease in mass by no more than 50%

Gypsum boards do not meet these requirements and are therefore assigned to group D (combustible).

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Drywall flammability group

Combustible building materials also have their own classification and are divided into four flammability groups: G1, G2, G3 and G4. The table below illustrates the standards that a material must meet in order to obtain one of the four groups.

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The specified parameters refer to samples that have passed tests on the test of my Method II, according to GOST 3024-94. This method involves placing the sample in a combustion chamber, in which it is exposed to a flame on one side for 10 minutes so that the temperature in the furnace is in the range from 100 to 350 ° C, depending on the distance from the lower edge of the sample.

This measures the following characteristics:

Flue gas temperature
Time for flue gases to reach their highest temperature
Weight of the test piece before and after the test
Dimensions of damaged surface
Does the flame go to that part of the samples that is not heated
Duration of burning or smoldering, both when heated and after exposure has ended
Time for the flame to spread over the entire surface
Is the material burning through
Is material melting occurring
Visual modification of the appearance of sample

After collecting and analyzing all the above indicators obtained in laboratory conditions, the material is assigned to one or another combustibility group. Based on the figures that were recorded when testing a GKL sheet with dimensions of 1000x190x12.5 mm according to Method ll described above, it was found that the drywall combustibility group is G1. According to this group, the temperature of its flue gases does not exceed 135 ° C, the degree of damage along the length of the sample is not more than 65%, damage by weight is not more than 20%, and the self-burning time is zero.

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Video

See the following video for a demonstration of drywall fire testing:

Fire Class u 670 kg / m³ and thickness 12.5 mm according to GOST 30403-96 are classified as fire hazard class K0 (45). This means that when the unloaded material was exposed to fire for 45 minutes, no vertical or horizontal damage was recorded in it, and there was also no combustion and smoke formation.

At the same time, in practice, the bearing capacity of a single-layer plasterboard partition is lost after 20 minutes of fire exposure to the material surface. In addition, it should be borne in mind that the fire safety of a particular drywall partition will depend on its design. Is it installed on a metal frame or on a wooden crate, is there a layer of insulation inside and is it combustible.

[attention type=yellow]In addition to fire hazard and flammability, drywall also has properties such as combustion toxicity group, smoke generation group, and flammability group.[/attention]

According to the toxicity of combustion products, GKL sheets are classified as low-hazard (T1). The smoke-generating ability of the material characterizes it as having a low smoke-generating ability (D1) with a smoke generation coefficient of not more than 50 m² / kg (smoke optical density). For comparison, smoldering wood has a value of this coefficient equal to 345 m² / kg. The flammability group of drywall B2 is moderately flammable materials.

what materials to use, how not to break the law – expert opinions – Kommersant Chelyabinsk

The spring-summer season in the Urals was marked by great attention to the topic of fire safety. The construction of a building for a business or a residential building – multi-apartment and private – always raises the issue of fire protection. What does the market offer? There are non-combustible plasters, paints, etc. There is constructive fire protection. These are structures made of various fire-resistant materials. The latter is preferable for a number of reasons. Judge for yourself: in order for the paint to work as a wall protection during a fire, it must be applied in a thick and very even layer, which is quite difficult. In addition, there are a large number of paints on the market that receive certificates, but in fact do not withstand fire tests. As for the structures, here are both aesthetics (for example, you can stick any wallpaper on columns lined with GVL), and convenience (GVL does not require periodic updating, unlike paint), and the best fire retardant result. Let’s talk about the latter in more detail with our experts.

GVL in the construction of residential buildings

IC “Legion”:

– For the design of residential buildings, there are two main regulatory documents related to the safety of the building. These are FZ-384 “Safety of buildings” and FZ-123 “Fire safety”. In their support, SP, SNiP, GOST were created. The development of our projects is carried out in full accordance with these documents. Derogations from them are impossible at the legislative level. Compliance with the requirements of these standards guarantees the safety of people in the house.

The project specifies all the characteristics of the materials used with a possible run-up, if it can be allowed by the regulatory documentation. The selection of material is carried out strictly with the instructions of the project! Replacement is possible only with a material with the same characteristics or higher, but not lower than those indicated.

The fire protection market now offers a wide variety. But you should trust only proven materials, since human safety is much more important than saving money. We purchase GVL, GKL and profile from Knauf.

GVL is used for the construction of partitions, as well as for sewing engineering networks, for which it is necessary to fulfill the fire resistance limit during the passage and which do not need access for maintenance. The required fire resistance limit is selected according to the manuals and recommendations of the manufacturer.

Igor Ternovsky, General Director of Pioneer Engineering Company:

– In residential buildings, fire safety by and large means the lives of residents. If we talk about the “King Plaza” (the tallest building in the city, the project of Pioneer LLC. – Author’s note), then the requirements for fire safety are increasing dramatically. Because it’s a 25-story building. This building is the highest – the first degree of fire resistance. All materials that are used in the construction and decoration of the “King Plaza” are of the same class – only non-combustible. This is reinforced concrete, brick, tile. That is, neither walls, nor ceilings, nor ceilings burn. If the fire blazes for several hours, the building will not collapse – people will have time to evacuate. For interior decoration, that is, for partitions, we use gypsum fiber and gypsum plasterboard sheets from the manufacturer Knauf. These are non-combustible high-quality materials that are perfect, including for buildings such as ours.

Vasily Livanov, Head of Knauf Sheet Materials Department:

– Knauf offers a wide range of solutions for fire protection of premises and structures: Partitions, ceilings, fire protection of metal columns and beams, and even fire protection of wooden structures. Knauf produces a wide range of sheet materials, but most fire protection tasks can be solved with Knauf-supersheet gypsum-fiber sheets. Structures using GVL withstand all possible tests and are excellent for solving fire protection issues of load-bearing building structures and system solutions for soundproofing structures.

GVL (Knauf-superlist gypsum-fiber sheet) is vandal-resistant (due to its increased strength it withstands loads much more than standard GKL), moisture-resistant (can be used in rooms with high humidity) and environmentally friendly material. Provides not only ecological cleanliness, but also a microclimate favorable for a person in the room. The material does not contain toxic components and has an acidity similar to the acidity of human skin, fire resistant (GVL constructions provide the possibility of evacuation up to 4 hours) ideal for any kind of finishing.

Knauf-superlist is distinguished by a combination of high fire-technical, strength, soundproofing and other characteristics that meet the requirements for sheet finishing materials and products made from them.

This allows GVL to be widely used for element-by-element assembly structures with skins made of Knauf supersheets. They are intended for use in residential, public and industrial buildings (these are shopping and entertainment centers, office centers, production workshops, warehouses, residential and private houses): all degrees of fire resistance, including I degree; all classes of constructive fire hazard, including CO class; all classes of functional fire hazard, including class F1; any constructive systems and types; any level of responsibility, including increased; different number of storeys; regardless of the climatic and engineering-geological conditions of construction.

Security in shopping centers

Olga Kuznetsova, head of the marketing department at Rodnik LLC:

– In April, Rodnik, Almaz and Ural shopping centers were involved in repeated large-scale inspections. The organizer was the Prosecutor General’s Office of the Russian Federation with the participation of the Ministry of Emergency Situations, the Russian Guard, the traffic police, Rospotrebnadzor and Gosstroynadzor. The compliance of building structures, as well as finishing materials and equipment with fire safety standards, the performance of warning and fire extinguishing systems, the layout and maintenance of evacuation routes, and the readiness of shopping center employees to evacuate visitors were assessed. Based on the results of the checks, an act of the Ministry of Emergency Situations was issued, confirming the absence of violations by the owner of the shopping center, i.e. in common areas. Comments were submitted to shops and entertainment establishments, where their projects and their responsible persons. They were given time to fix it.

The safety of visitors has been, is and will be a paramount task, which has been addressed by professionals at all stages of life. Around the clock at our facilities, from 100 to 150 people are responsible for security, regularly undergoing professional training. The design of shopping centers was carried out by specialists with world experience. Only permitted building materials were used in the construction and decoration.

Vasily Livanov, Head of Knauf Sheet Materials Department:

– Federal Law No. 123 “Technical Regulations on Fire Safety Requirements” stipulates what materials can be used depending on the functionality of buildings, the number of storeys, the capacity of halls, etc. A big mistake of some contractors is that they neglect this by law. Save money by choosing cheaper materials. Therefore, some construction projects were built with violations. For example, they make the fire protection of load-bearing building structures with fire-resistant drywall, and not GVL. This leads to the fact that if the supervisory authorities reveal the forgery of materials, the contractor, at his own expense, redoes all stages of work performed with violations. And if the forgery is not detected, then this can lead to irreparable consequences during the operation of the construction site. Knauf managers visit the facilities free of charge and provide technical advice on all systems provided by our company. But there are clients who do not consider it necessary to listen to specialists, and as a result, the miser pays twice.

Knauf has a training center, where the manufacturer of materials demonstrates to builders, contractors and designers the differences in materials, the correct installation of manufactured systems.

Attention to fire class

Andrey Smirnov, Head of the State Fire Supervision Department for Chelyabinsk:

– This year, together with the prosecutor’s office, unscheduled inspections of objects with a mass stay of people took place. In Chelyabinsk, these are 70 facilities: 25 sports, 21 cultural, 8 children’s leisure and 16 shopping and entertainment centers. Checks have shown that there are many violations. There are no ideal buildings in this regard. This is not to say that the norm is commonplace. But there are gross violations and minor ones that can be corrected fairly quickly. As for violations related to materials, they also exist, but they are few. Because all such facilities are built according to special technical conditions, which impose rather stringent requirements for interior decoration. It happens that some materials are declared in the plan, and the object is built from others. This happens when, during operation, the object is handed over to a third-party legal entity and it makes repairs in its own way. Each facility has a fire safety engineer who must monitor this.

The law regulates the requirements for materials for finishing halls and escape routes: corridors, halls, foyers, vestibules. They are subject to requirements for finishing walls, ceilings, floors. Materials must be certified for fire hazard properties in different groups: combustibility, flammability, etc.

Such violations occur when either non-certified material is used or material with inadequate characteristics in the certificate. For example, a group of “slow-burning” is required, and “moderately combustible” is used – that is, a more combustible material. Finishing with some kind of panels or siding, of course, will be cheaper than certified materials. Someone violates in order to save money, and this is already negligence, dishonesty of the facility manager. Others – because of ignorance of fire safety requirements, which also does not exempt from responsibility.

Vasily Livanov, Head of Knauf Sheet Materials Department:

– A big mistake when they pay attention only to the flammability group. You should always look at the fire rating of the material, as required by federal law. The fire hazard class of building materials is characterized by the following properties:

flammability;
flammability;
ability to spread flame over the surface;
smoke generating capacity;
toxicity of combustion products

Drywall, even fire resistant, class KM2. At GVL – KM1. The difference is in flammability and toxicity.

When designing buildings and structures, not only the fire hazard class of materials is important, but also the fire resistance limit of structures. Knauf has both fire safety certificates for materials, as well as reports and conclusions of tests carried out on structures (partitions, ceilings, etc.).

How do we test?

Tests are being carried out in the testing laboratory of the Fire Safety Research Center of the Federal State Budgetary Institution VNIIPO EMERCOM of Russia. The structures are placed in an installation (furnace) for testing the fire resistance and spread of fire of the supporting structures, and a fire is simulated at a temperature of 1000 degrees Celsius. Among other parameters, the time until the destruction of the structure or the occurrence of a certain deflection is taken into account. Different rooms, depending on their purpose, have different requirements for structures.

Metal is often used in the construction of fuel dispensers in load-bearing structures. Metal under prolonged exposure to fire loses its properties, becomes more ductile. In case of fire, if the fire affects the supporting metal structures without proper fire protection, then the roof, interfloor ceilings or other elements of the building may simply collapse. Therefore, GVL is used for fire protection of steel structures. The fire resistance limit of such structures is up to 150 minutes. GVL is also used for cladding wooden structures. The fire resistance limit of attic floor structures made of wooden structures with GVL sheathing is up to 75 minutes. The more people in the room, the more time is needed for their evacuation and the higher the fire resistance limit of structures should be. Therefore, in rooms with a mass stay of people, two-layer partitions with a fire resistance limit of 9 are used.0 – 120 minutes. Three-layer partitions give 4 hours.

Construction Supervision Control

Head of the Department of Regional State Construction Supervision of the Ministry of Construction and Infrastructure of the Chelyabinsk Region Evgeny Efimenko:

– In accordance with Part 2 of Art. 54 of the Town Planning Code of the Russian Federation, the State Construction Supervision checks the compliance of the building materials used with the requirements of technical regulations and project documentation that has received a positive expert opinion. This includes checking documents confirming the quality control of the building materials used.

With regard to the control of works that are hidden by subsequent types of work (for example, the internal construction of a partition), in these cases, the as-built documentation is checked. These are, among other things, certificates of examination of the work of building structures, sections of engineering networks, engineering systems and equipment that affect safety, the control over the implementation of which cannot be carried out after the completion of other works, as well as without disassembly or damage to building structures .

Specialists of the Department of Regional State Construction Supervision, regardless of the direction of work, are trained and attend construction conferences as far as possible.

Vasily Livanov, Head of Knauf Sheet Materials Department:

– When Knauf develops new developments, we strive to bring their results to the attention of designers and regulatory authorities.

Type X vs. Type C Drywall

What is fire-rated drywall?

Type X drywall

Type C drywall

How does fire-rated drywall work?

Where is fire-rated drywall required?

Conclusion

Build Smarter

Types and Uses of Fire rated Drywall

HOW TO CHOOSE A WET DRY VACUUM

How Many Drywall Types Are Out There and Is All Drywall Fire Rated?

How do You Know if Drywall is Fire Rating?

Drywall combustibility group

Drywall combustible or non-combustible?

Drywall flammability group

Video

what materials to use, how not to break the law – expert opinions – Kommersant Chelyabinsk

GVL in the construction of residential buildings

Security in shopping centers

Attention to fire class

Construction Supervision Control

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