Fire-Resistant Buildings: How Are They Classified?

You might think that contractors constructed most commercial buildings using the same methods and materials. However, they made each one by utilizing different construction processes. The client might have a different building design in mind, so the contractor needs to adapt and alter their style. One part of the construction process that doesn’t change is using fire-resistant materials for the building. You can define each fire-resistant structure through its classification types, ranging from Type 1 to Type 5. 1 has the highest fire resistance while 5 has the lowest. Understanding each classification type is a means to achieving the best fire-resistant building.

Type 1: Fire-Resistant Buildings

As mentioned before, Type 1 is the highest classification for fire resistance. Type 1 fire-resistant buildings can stand as tall as 75 feet, and those facilities included in that classification type are commercial spaces and high-rises. Type 1 buildings are the most sturdy during building fires because of the design and materials used. They can withstand extreme temperatures from the flames for hours without collapsing.

When firefighters encounter burning Type 1 buildings, they prioritize stairwells because it’s where people usually pass through to escape. Other keynotes you should learn about Type 1 buildings include:

Strengths: They have non-combustible structural materials, which can last up to four hours. It’s also resistant to collapse.

Weaknesses: Steel materials in fire-resistant buildings Type 1 will wear out over time due to different harsh elements like rust. People will have difficulty breaking through windows and roofs to provide ventilation during a fire.

Type 2: Non-Combustible Buildings

Some examples of Type 2 buildings are big shopping malls and “big-box” commercial establishments. Even if the buildings have fire suppression systems or fire-rated access panels for all surfaces, they can collapse due to metal roofs. Remember that metal roofs will fail when exposed to extreme temperatures, even if the flames don’t hit them directly.

Firefighters sent to put out Type 2 burning buildings will focus on providing ventilation. They can do this by breaking through the roof, window, doors, or anything that can let smoke escape out of the building. They also do it to prevent flashover, which is the sudden spike of temperature that can cause fatalities. Some of the building’s strengths and weaknesses include:

Strengths: Type 2 buildings only have one or two hours of fire resistance, depending on the contractors’ materials.

Weaknesses: Temperatures can quickly shift if the building can’t provide sufficient ventilation. It’ll eventually lead to the roof collapsing after the two-hour limit.

Type 3: Ordinary Buildings

As the name suggests, the Type 3 classification refers to old and new buildings such as schools, houses, and businesses. It utilizes “ordinary” construction that comprises non-combustible walls with walls made from wood material. However, not every Type 3 building will have wood roofs because older buildings usually have traditional framed roofs, while newer ones utilize a lighter roofing system.

In a building fire, firefighters have to determine if it is new or old before making any choices in providing ventilation.

Strengths: Exterior walls can still stand firm even if the floors collapse because of the combination of fire-cut joists and non-combustible masonry.

Weaknesses: Most Type 3 buildings have interconnected horizontal empty spaces and attics, causing the fire to spread faster unless contractors installed fire stops.

Type 4: Heavy Timber Buildings

You can define old 1960s buildings as Type 4 classification because they mostly use large lumber pieces. Firefighters can recognize Type 4 buildings without a problem because the lumber structure stands out from modern buildings and structures. Builders connect the lumber pieces using metal bolts and plates, strengthening the structure.

Strengths: Load-bearing walls are sometimes non-combustible. It can also often have drains, allowing the water from firefighters to exit the structure without damaging the timber structure and possible collapse.

Weaknesses: The metal joints connecting the lumber pieces can fail or melt at extreme temperatures. Buildings riddled with oil or machinery can cause the entire heavy timber building to catch on fire rapidly.

Type 5: Wood-Framed Buildings

Most residential buildings will have the Type 5 classification because of the high volume of combustible materials used during their construction. You can find tons of wood materials in homes that contractors mainly use to build the walls and roof. The upside with wood-framed buildings is they don’t cost as much compared to heavy timber buildings.

Remember that Type 5 structures will collapse instantly, so the occupants should put out fires before firefighters arrive. If firefighters arrive at the scene while the building is still burning, they can create ventilation right away since it’s easy for them to break through the wood materials. They need to consider where they plan on making a hole in the wood structure as one heavy force can cause it to collapse.

Strengths: Using larger beams can prevent Type 5 buildings from collapsing. The flipside of using them is they cost a bit more than lightweight beams.

Weaknesses: Wood materials burn easily, and modern construction methods can put the entire building at risk of fire spreading faster.

Keep in mind the different classification types for Fire-resistant buildings to help you understand the type of your building. It can also help you find the best ways to achieve high levels of fire resistance.

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