When starting a construction project, it is important to understand what combustible materials are and how they are different from noncombustible materials. Combustible materials are at risk of catching fire and spreading the fire to other parts of the building, whereas noncombustible materials are non-flammable and much safer.
There are pros and cons to using each option, and it is not necessarily dangerous to use combustible materials. However, buildings that are Type II, IV or V, which are buildings constructed primarily of either treated or untreated wood, should have more safety precautions in place to prevent the start and spread of a fire.
The following is an overview of what combustible materials are, including how they differ from noncombustible materials, the benefits of treated for use in construction and safety requirements related to combustible materials.
Combustible vs Noncombustible
Combustible refers to any material that will catch on fire and burn. As it relates to building materials, almost all types of lumber are considered combustible. This is important to understand as it can affect how it can be used based on the type of construction.
Noncombustible is the opposite. Noncombustible materials refer to construction materials that will not ignite, burn or release flammable vapors. The use of noncombustible materials plays a role in the type of construction. It is safer and more reliable in predicting fires within a property.
Whereas most wood types that are used for construction purposes are considered flammable, there are still many building materials that are noncombustible. Examples of noncombustible building materials include brick masonry, concrete blocks, cement, metal and sheet glass.
Certain buildings might need to be Type I or Type II for optimal safety. This means the majority, if not all of the building, consists of noncombustible material. Most buildings have few restrictions, but it is still strongly encouraged to use treated wood to reduce the risk of a fire.
Treating for Use in Construction
Wood is naturally combustible. This means that buildings with wooden walls, floors and roof are at an increased risk of a fire. Fortunately, however, there is a way to use lumber in a way that still significantly reduces the risk of a fire. The solution is known as fire-retardant-treated wood (FRTW).
Fire-retardant-treated wood is wood that is made more resistant to ignition and fire spread through the use of retardant chemicals. It starts out as kiln-dried wood before going through a detailed and thorough process to make it less combustible.
Using treated wood as opposed to untreated wood can make a building much safer. A Type V construction refers to a building that is made of wood that is not fire treated, and buildings that are made of fire-treated wood are considered either Type III or Type IV constructions, which is considered safer.
In most instances, fire retardant wood is worth the investment. Although it might appear slightly darker, it is attractive and does not differ by much. It is also durable and able to be used both indoors and for the exterior and roof of a building. The only notable difference is that fire-retardant-treated wood is safer.
Safety Requirements
Depending on the purpose of the building and the risk of a fire, there might be federal- or state-specific safety requirements that dictate how much combustible material is allowed during construction. If there are applicable safety requirements, it will most likely be dictated by building type requirements.
The differences between combustible and noncombustible materials are important to understand for those who plan to start a construction project. As mentioned, whether the building materials are combustible or noncombustible dictates the type of construction. Section 602 of the International Building Code (IBC) has five construction types, which are Type I through Type V.
Types III, IV and V have few restrictions as it relates to the use of combustible materials, namely wood. These buildings can be made exclusively of wood if desired. The difference between Types III through V deals with the type of combustible material. Type III and IV use fire retardant treated wood. Type V is a typical wood-frame building. Many residential homes are Type V.
Types I and II place restrictions on the use of combustible materials. Type I is made entirely of noncombustible building materials, including the roof. For Type II, the walls, floors and structural framework is noncombustible but the roof is combustible.
Speak with a Wholesale Lumber Supplier
To learn more about what combustible materials are and find out what building materials you should use for your construction project to ensure optimal safety, reach out to our team at Curtis Lumber & Plywood today.
We sell different types of treated wood and other products. We can guide you through the decision-making process of your construction and answer any questions you may have.
