Why do buildings fall?

There are many reasons buildings can collapse, but most people can identify the cause by the structure’s shape once it has settled. Loss of stability is the main reason a building can collapse. When a particular force or combination of forces impacts the structure and integrity of a building, this is called collapse. The party will cause the building to collapse and change its shape and form to be more stable. Buildings can collapse for many reasons.

Factors that could cause a collapse


If a building is caught on fire, it will be exposed to high temperatures, which can cause some building elements to expand. This can lead to roof collapse and weakening of floors, as well as walls being forced out of their shape. To put out a fire, water is added to the structure to increase stress on the upper floors, which can lead to failure.

Geological Effects

Natural or geological events could also destroy a structure. Earthquakes and landslides can move the earth horizontally or vertically, putting more stress on the system than it can handle.

Waterlogging can also cause the ground where the structure is constructed to become unstable and eventually collapse. Liquidation is the most common cause of collapse on a coastline.

Extreme Weather

A structure in an area with high winds is more likely to collapse. Although the wind alone is not enough to cause the structure’s collapse, it could blow off its roof, creating suction and significant pressure within the system, leading to failure.

Flooding or a lot of rain could cause a structure’s water level to rise, which could displace air and cause pressure to shift. A system could also collapse if it is covered with snow, particularly if the roof has a flat roof.

Structural Defects

Sometimes, a structure can fall due to poor design or materials. Contractors don’t allow the concrete slab to be appropriately set before removing the stabilizing brats. This causes the slab’s support to give way, and the slab falls to the floor below. This can often lead to multiple floors collapsing.


Although this force can be categorized as intentional or accidental, it is always artificial. There is always the possibility of secondary collapse when there are explosions. Due to the additional load they carry upon the blast of another building, buildings next to it may also collapse.

Leakage of gas can cause a structural collapse. A backdraft could be caused by air being rapidly introduced into a compromised building. A dust explosion or the detonation in a structure of volatile materials could also cause total failure.

Recent events have shown that terrorist acts have caused most of the intentional collapses. The Oklahoma City Bombing and 911 are two examples. A shockwave of compressed air is produced when an explosive is placed within a structure. This can cause additional damage to the system.

External detonated explosions can produce shockwaves that magnify and penetrate the structure through natural openings. The shockwave will put enormous pressure on the walls and roof and could cause damage to the system.

Transportation Emergencies

Transport such as aircraft, trains, and road vehicles could collide with buildings, causing a partial or complete collapse. The severity of the failure will depend on the size and purpose of the car.

Interior Collapse Patterns

This section will discuss the different types of collapse and whether voids have been created. A hole is an area below or within the clear debris and where there are the best chances of finding survivors. The type of void formation is dependent on the collapse type.


The load-bearing walls collapse, causing the floors above and below to collide. This is a catastrophic event, and very few voids are usually left after the structure has settled. This collapse is caused by furniture and appliances that disrupt the stacking effect. This collapse is the most difficult and involves extensive searching for survivors and a long period of debris removal.


A floor can collapse when one of its supporting walls, beams, or columns fails, causing it to tilt down and creating a triangular-shaped void. This type of collapse creates a giant vacuum that increases survivors’ chances.

Lean-to (Supported)

The collapse occurs when the floor’s collapsed end is placed on top of the debris, furniture, or machinery. This means that both ends of the bed can be supported.

Lean-to (Unsupported)

The collapse occurs similarly to the supported-lean-to collapse, except the failed end hangs above the floor below. This case has no support, and the failed end can only be held together with reinforcements and other binding elements within the flooring. This is dangerous and must be stabilized before rescue and search procedures begin.


The upper floor collapses when it is under too much load. This causes two triangular voids to form on each side. This allows survivors to be located in a greater area. Victims on the top floor would fall in the direction that the collapse is occurring and could be trapped under the debris. This would require a variety of tools to cut through the trash.

A Frame

This is the opposite of the V collapse. This happens at the exterior walls, but they are still supported by one or more interior load-bearing or not-load-bearing walls. Explosions, earthquakes, and liquefaction can all cause the A-Frame to collapse. Near the central part of the collapse is the partition wall. This is the best area to look for survivors. There is less chance of finding survivors if you go towards the exterior walls.

Exterior Collapse

90* Angle

The wall collapses when it falls from the structure at a distance equal to its height. This results in debris being spread to the ground. Structural fires can cause this type of collapse. Only in the area of destruction will you see the void formation.

Curtain Fall

This is when a wall falls to the ground, causing a heap of debris at its base. This type of collapse will not likely leave any voids.


This is when a horizontal crack in the wall forms around the center line. Both halves will fall in opposite directions, with the top half of the structure falling in and the bottom falling out.

Total Collapse

Total collapse is the most severe type of collapse. This is when all walls collapse onto the floor, causing all floors to collapse to the basement or ground.

Basement Collapse

Basement collapse rarely occurs. This is when the ground floor falls into the basement, leaving the upper floors intact. If the ground floor is a shopfront, the upper floors might tilt forward, making them unstable. It isn’t easy to find survivors in the basement. During rescue and search, it is essential to monitor the stability of the entire structure.

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