We use buildings daily; however, most people do not know how to construct them or the type of construction that influenced them. Different regulations govern different construction types, and it is essential to find out the category in which your project falls. A good understanding of your building's construction type is necessary to effectively design services such as fire fighting. Analyzing the critical insights of your project from an architectural and engineering perspective helps us to question our conventional awareness in construction.
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What does construction type mean?
Construction type refers to how a building is resistant to fire. This includes all the structural members and non-load-bearing components of the building. The choice of materials and design of a structure affect a building's resistance to fire, earthquakes, and other related phenomena, thus affecting the construction type. There are five major construction types widely recognized in the construction industry.
Why is determining construction type important?
Understanding the construction type of a building is vital information for firefighters and the building's users. When firefighters can easily identify a construction type, they can quickly plan their line of attack. Understanding how fire spreads helps make critical decisions on ventilation and water. A keen sense of construction types, therefore, helps save lives.
The construction type also affects a building's resilience to unforeseen catastrophes like hurricanes and earthquakes. In the same way, construction workers are wary of accidents during construction; they should be aware of how their work affects the building's future safety.
The five different types of construction types
At first glance, most buildings look similar. However, the underlying materials primarily affect the durability of a building. We classify projects from Type 1 to 5, mainly depending on how fire-resistant a structure is. Some facilities are more vital and cheaper to construct, but they do not handle fire well. Type 1 buildings have the highest fire resistance, and type 5 structures have the poorest fire resistance. Without further ado, let us cover the different construction types.
Type 1: Fire-resistive
Generally speaking, Type 1 buildings are high-rise residential and commercial spaces. These buildings are made mostly from concrete and steel, and we classify them as the most robust during a fire. They can withstand high temperatures for a long time. These ratings apply to roof and floor assemblies, internal partitions, and bearing and support walls. The strengths of these buildings are that they are not vulnerable to collapse, and they are fire-resistant for up to four hours. The weakness of these buildings is if they are made of steel, they wear down over time due to corrosion. The roofs and windows of these buildings are also not easily penetrable in fire times. Some of these buildings have pressurized stairwells to curb the spread of fire.
Type 2: Non-combustible
Most modern "big box" stores and shopping malls qualify as Type 2 buildings. We majorly make these buildings from lightweight concrete, metals, and masonry, which are primarily non-combustible. However, there might be combustible materials present such as foam and rubber. These buildings have sound fire suppression systems but are prone to collapse, mainly because of their types of roofs. In a fire, firefighters try to ventilate the building to mitigate flashovers which are sudden temperature increases. These buildings burn for one to two hours, depending on the type of materials used in construction. The materials of these buildings are slow-burning, which ends up adding fuel to the fire. In a fire, firefighters ventilate these buildings using roll-up doors or skylights to a building's exterior.
There are significant differences between type 1 and type 2 buildings. Type two buildings are susceptible to expansion, relaxation, and distortion of steel members resulting in an almost total collapse in case of fire. The interior partitions of these buildings are made from non-combustible materials and some limited approved combustible materials. Examples of these types of construction are modern school buildings.
Type 3: Ordinary type
We also refer to these building structures as brick and joist structures. These structures have walls made from bricks or masonry, wooden roofs, and floors that are not fire protected. In most cases, all or part of the interior elements such as frames, floors, and ceilings are made from combustible materials. All type three buildings have wooden roofs, but conventionally, older type 3 buildings have framed roofs, but new buildings have lightweight roofing systems. The walls are either reinforced masonry or concrete. When firefighters approach a type 3 building, they have to determine whether it is old or new to make critical decisions on ventilation. Both new and old buildings fall in the ordinary construction type category. Some of these buildings are schools, residential and small commercial buildings.
An advantage of these buildings is that their combination of materials allows them to stay standing even if floors collapse. Their major weakness is that many connected attics or void spaces enable fire to spread rapidly.
Type 4: Heavy timber type
Most of the buildings constructed before 1960 were heavy timber-type buildings. They are easily recognizable by firefighters as they have timber walls and roof spans. The timber members are either solid or laminated, and they must fit dimensional requirements. Examples of such buildings are old factories, churches, barns, and residential houses. Structural supports such as beams, arches, and columns require a minimum of eight inches for these construction types. Sometimes these buildings may have non-combustible load-bearing walls. They also quickly drain water, allowing the firefighters' water to quench the fire to seep out easily without increasing the overall building weight. Most of the connections are metal joint connections that fail quickly during fires. In the case of factories, oil, goods, and materials can increase the severity of the fires. Large dimensional timber buildings hold up well during fires, but damage from weather and termites increase their risk of collapse.
Type 5. Wood-framed type
Many new modern homes are Type 5 construction types. This is because they use combustible materials for the walls and roof. Unlike the large dimension wood used in heavy timber type buildings, we make these structures from lightweight or flammable manufactured wood. This construction is easy to set up, inexpensive, and structurally sound. It, however, is not fire resistant and collapses within minutes in the event of a fire. However, firefighters can deal with these buildings as they are well ventilated from the wood frames. This is also a disadvantage as the fire spreads rapidly due to the high ventilation. One way to prevent the collapse of these buildings is by using big timber members for the main structural elements. This prevents collapse and strengthens interior platforms. Overall, these types of structures have deficient fire-resistant properties.
How to determine the construction type
Several factors affect a building's construction type. Below are aspects you need to consider when determining a construction type.
The purpose of a building affects construction aspects such as materials and the project scope. Huge commercial buildings undergo different construction methods compared to their smaller counterparts. Some building classifications according to purpose are educational, institutional, commercial, industrial, and residential. The purpose of the building affects the choice of building materials which in turn affects the building type. Examples of building materials used are bricks, hollow concrete blocks, stones, and tiles.
Generally speaking, more significant buildings use heavier construction types. They will have floor spaces with long spans and heavily supported roofing systems. Smaller buildings have limited spaces and are not fire-resistant. The building size also affects the sprinkler thresholds and fire areas, and the law mandates for design and installation of fire protection systems for big buildings, thus affecting the building type. Fire areas are areas enclosed by exterior assemblies and fire barriers. High occupancy buildings have these fire areas compared to smaller facilities.
3. Load bearing constraints
As a building increases in size, it affects its capacity to bear loads. A construction type must be robust enough to handle excess loads. For instance, wood is terrible for supporting a superstructure with several floor levels. Heavy loads cause deformations and stresses in a structure. For example, load-bearing masonry performs poorly in terms of collapse during a fire or earthquake. However, to build a fire and earthquake-resistant structure, one has to choose a higher construction type.
Buildings of a lower construction type are faster to erect. This is because the time necessary for design and construction is less. The labor needed is also less, and the construction materials can facilitate faster building. For instance, to speed up construction, one can use pre-engineered methods and prefabricated construction types that are dropped to the construction site and quickly erected.
The cost of a project largely determines the construction type. This is because the price affects the choice of materials, the quality of labor, artistry, and project scope. Lower construction project types require less money compared to higher construction project types.
6. Environmental factors
The environmental factors affect the choice of buildings that we can erect there. In coastal areas, buildings are elevated to shelter them from tidal surges. The choice of materials and design for buildings in earthquake-prone regions is also different compared to typical areas. A stiff structure easily collapses during fires and tremors.
By now, you have a good idea of the different construction types available. By understanding the various construction types, we better appreciate the buildings we live in. Understanding construction types is important information for the safety of the buildings and helps give people a keener sense of what to anticipate in dangerous situations.