What are the 5 Types of Building Construction?
Most people would look at a building and view it as just that: a building. But as a contractor, you see buildings differently. Building elements like the structure, walls, floors, and roof are all telling of a building’s class. If you don’t already have a keen eye for those details, it’s important to know the five types of building construction. Especially if you’re in the fire restoration business. Buildings can be categorized into five different types of construction: fire-resistive, non-combustible, ordinary, heavy timber, and wood-framed.
Fire-resistive Type I (IA and IB)
With this type of construction, walls, partitions, columns, floors, and roofs are the most noncombustible when it comes to fire-resistant ratings. These structures are usually easy to spot based on their height. Fire-resistive buildings are more than 75-feet tall and made of poured concrete and protective steel. They are designed to withstand the effects of fire for a long period of time to prevent a fire from spreading. Ventilation in these types of buildings is not an option because the roof must also be composed of noncombustible materials.
Non-combustible Type II (IIA and IIB)
Non-combustible buildings are similar to the fire-resistive type where walls, partitions, columns, floors, and roofs are noncombustible. However, they provide less fire resistance and do not withstand the effects or spreading of fire as well as Type I. This type gets its name “noncombustible” not because of its resistance to fire, but because of the fuel the building contributes. Newer school buildings are common examples of this type of construction. These buildings typically have a metal floor and metal roof with masonry or tilt-slab walls. They are the least stable in terms of collapse when exposed to fire.
Ordinary Type III
These buildings are also called brick-and-joist structures. This type of construction has brick or block walls with a wooden roof or floor assembly which is not protected against fire. All or part of the interior structural elements (frame, floors, ceilings, etc.) is combustible/wood. Verticle ventilation in these types of buildings is possible. You will see ordinary construction in both old and new buildings.
Heavy Timber Type IV
Type IV buildings have noncombustible exterior walls and interior elements. These buildings are made out of solid or laminated wood. All wooden members must meet dimensional requirements. Wood columns, beams, and girders must be at least 8 inches thick. Heavy planks for floors and roofs must be at least 6 inches thick. If these types of buildings catch fire, they require large volumes of water to extinguish, but they hold up well against fire and don’t collapse easily due to their structural mass.
Wood-Framed Type V
Wood-framed buildings are the most combustible out of all the types. They are the only construction type that allow combustible exterior walls. Type V also allows a combustible interior (structural frames, walls, floors, and roofs) made entirely or partly out of wood. This type is commonly found in modern homes. They often have exposed wood so there is no fire-resistance. It ignites significantly but is reasonably resistant to collapse unless it is a lightweight construction, in which case it will fail within minutes.