What are the Different Types of Construction?

April 6, 2021

If you’ve ever spent a night in the city and woke up to the sounds of screeching metal, then you’ve encountered construction. To those outside the industry, the process blurs together an intimidating collection of machines and parts. But those working within it know the industry remains highly organized, broken down into specific types of construction and processes. Keep reading to find out more.

The 5 Types of Building Construction

combustible materials are less fire-resistant than non-combustible materials

There are lots of different ways to classify construction projects and categorize buildings. Things are often broken up according to the owners, materials used, or types of structures. But there’s another way to divvy things up, and it revolves around the necessary level of fire resistance a building contains. This list is called the 5 Types of Building Construction, with the first following the most stringent fire resistance requirements and the fifth following the least. Check out the list below for more information.

Type I Construction: Fire Resistive

This category applies to any building that stands over 75 feet tall. This applies to all high-rise housing and commercial space. That includes apartment buildings, offices, and hotels. These buildings are designed to withstand high temperatures for a long time without collapsing. Beyond that, all structural materials are non-combustible. Walls, floors, and roofs are constructed with reinforced concrete and protected steel. While these features make these buildings extremely durable, it also increases construction costs.

Some Type 1 buildings have HVAC systems and self-pressurizing stairwells to prevent fires from spreading. These building elements make it easier for firefighters to access and extinguish fires. When entering a Type 1 building, their main objective revolves around securing stairwells to ensure a safe evacuation.

Type II Construction: Non-Combustible

Similar to the Type 1 buildings, Type 2 buildings contain non-combustible walls, partitions, columns, floors, and roofs. Though these structures typically contain fire suppression systems, they are not often protected with fire-resistive coatings and are prone to collapse. They typically contain metal floors and metal roofs with masonry or tilt-slab walls.

Newer school buildings, shopping malls, and recently renovated commercial structures typically fall under this construction type. If firefighters are called to a Type 2 building, their main priority will be to ventilate the building to prevent a dangerous rise in temperature.

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Type III Construction: Ordinary

Also known as brick-and-joist structures, Type III buildings consist of either tilt-slap or reinforced masonry walls. These materials are non-combustible. That is to say, some of the interior structural elements (frames, floor, ceilings, etc.) are made with wood or combustible materials. This kind of construction can apply to both old and new buildings. Old buildings will generally contain conventionally framed roofs, while newer units are typically built with lightweight roof systems.

Schools, buildings, and houses can all fall under this construction type. One of the perks associated with this construction type is that ventilation is possible. That said, many Type III buildings contain connected attics or horizontal void spaces, making fire extension more likely.

Type IV Construction: Heavy Timber

Type IV buildings are largely constructed using large pieces of lumber, connected using metal plates and bolts. This was a common practice before 1960, which makes heavy timber construction so easy to spot. Old churches, factories, and barns typically fall under this category.

This building type demands that all wooden members meet specific dimensional requirements. Structural wood supports such as columns, beams, and girders must be at least 8 inches thick. Heavy planks for roofs and floors must be at least 6 inches thick. Type IV buildings have noncombustible exterior walls and interior elements.

Though these buildings contain combustible materials, they generally fare well when exposed to fire. Their structural mass also makes them more resilient against collapse. Still, firefighters will require large volumes of water to extinguish a fire in this type of building. Metal joint connections can also lead to a rapid increase in fire severity.

Type V Construction: Wood-Frame

Type V buildings are the most combustible construction type on this list. It is the only category of construction that allows combustible exterior walls as well as combustible structural members on the interior. Frames, walls, floors, and roofs are made entirely or partly out of wood. These building elements are cheaper to develop and increasingly common in the construction of single-family homes and garages.

These structural elements can be particularly worrisome to firefighters, as exposed wood offers no fire resistance. If a  fire starts, the building will ignite significantly. These buildings may be somewhat resistant to collapse unless it is a lightweight construction. In that case, it will collapse within minutes of a fire breaking out.

What is the International Building Code?

exterior walls may have a different fire rating than interior structures

The International Building Code (IBC) governs the materials, systems, and assemblies used for structural fire resistance and fire-resistance related-construction. This is the resource we use to determine fire resistance ratings.

Each rating is measured in terms of the time a structural element can be exposed to fire before it collapses. So, for instance, a beam may be assigned a 2-hour fire rating. That means it can be exposed to fire for at least two hours. Materials with a fire rating of 0 will typically fail after less than an hour.

Fire Resistance Ratings, Defined

Each type of building construction is associated with different building elements, each of which varies in terms of fire resistance. The structural members associated with Type I construction generally receive three- to four-hour fire protection. The fire-resistance rating assigned to wood and other materials associated with Type IV and Type V construction often varies based on thickness. The American Wood Council’s National Design Specification for Wood Construction gives a nominal char rate of 1.5 inches of wood thickness per hour of fire resistance.

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FAQ

What tactics should ladder crews apply to the different types of construction?

Ladder crews have different procedures in place for different building types. When it comes to Type I construction, firefighters must be aggressive in securing stairwells and evacuating victims from the structure. With Type II construction, firefighters may consider opening skylights or resorting to natural ventilation. Depending on the roof system, they may also rely on similar ventilation operations for Type III and Type IV construction. Type V construction requires other alternatives, including but not limited to positive-pressure attacks.

What is the difference between Type A and Type B construction?

With the exception of Type IV construction, all tiers are divided into two subcategories: Type A and Type B. Type A refers to “protected” constructions, whereas Type B exists in reference to “unprotected” constructions. That is to say, Type A constructions offer more fire-resistant properties than Type B constructions.

What are the main types of construction?

In addition to the 5 types of building construction, there are different types of construction projects. These include residential building construction, industrial construction, commercial building construction, and heavy civil construction.

Conclusion

Understanding the differences between the five types of building construction is a necessary step towards a successful career in the field. If you’re interested in breaking into the construction industry, think about earning your degree from the New England Institution of Technology. We offer associate, bachelor, and master degree programs in building technology and construction management. You can fill out this form to learn more or call us at 401-467-7744.