After a building is hit by an airstrike, shelling or another blast, the fact that it is still standing does not mean it is safe to enter. Structural engineers and emergency teams assess whether key load-bearing elements have been compromised, whether the building is continuing to deteriorate and whether occupants can enter or remain without an unacceptable risk of collapse. In Gaza, that process is especially difficult because the scale of destruction, continuing hazards and shortage of engineering and emergency resources can prevent detailed inspections.
Authorities therefore use a layered assessment rather than relying on a single visible crack or damage category. Satellite imagery and aerial photographs can identify damaged structures across large areas, but determining whether a particular building is safe for people requires closer inspection of structural components. Gaza’s current emergency shelter guidance includes household-level visual checks, while professional assessments are needed for decisions about more serious structural damage and rehabilitation.
The first question: what was damaged?
A structural assessment begins by establishing how the building was affected.
An explosion can damage a building directly through impact and blast pressure, or indirectly through fire, debris and damage to neighbouring structures. Engineers look at the building’s overall geometry and at individual components such as:
- columns and beams;
- load-bearing walls;
- floors and slabs;
- foundations where accessible;
- staircases and balconies;
- connections between structural elements; and
- the roof and upper levels.
The crucial issue is not simply how much of the building looks damaged. It is whether the damage has interrupted the path through which the building carries its weight to the ground.
A damaged façade, for example, can be dangerous without necessarily meaning that the entire structural frame is failing. Conversely, damage to a column or major load-bearing wall can create a serious risk even when much of the building appears intact.
What inspectors look for
Cracks, distortion and movement
Inspectors examine cracks for their location, direction, width and pattern. They also look for signs that walls, floors or columns have shifted from their original position.
A diagonal crack can have a different structural significance from a superficial crack in plaster. Similarly, a floor that has visibly sagged or a wall that has tilted can indicate movement of structural components.
The assessment is not simply a visual search for “big cracks.” Engineers try to determine what caused the visible damage and whether that cause has affected the building’s stability.
Damaged columns and beams
Columns and beams are particularly important in reinforced-concrete buildings because they form part of the principal structural frame.
Inspectors may look for crushed concrete, exposed or bent reinforcement, spalling—the breaking away of concrete from a surface—and unusual deformation. Damage at the connection between a beam and column can also be significant.
Where these elements have suffered substantial damage, occupying the building may be inappropriate until a qualified engineer has determined that the structure can be stabilized or repaired.
Floors and staircases
A floor that has partially collapsed, separated from its supports or developed substantial deformation can create both a local and wider structural hazard.
Staircases receive particular attention because they are essential escape routes. A building may have standing walls and apparently usable rooms but still be unsafe to occupy if people cannot evacuate safely.
Signs of progressive deterioration
An inspection is also concerned with whether the building is stable now and whether it is likely to remain stable.
Water entering damaged structures, additional explosions, vibration, fire and removal of debris can alter structural conditions. A building that was judged temporarily stable immediately after an incident may require reassessment if its condition changes.
That is particularly relevant in Gaza, where humanitarian agencies have warned about the risks associated with damaged structures and approaching severe weather. A September 2026 UN assessment reported that hundreds of damaged structures were considered unsafe.
Satellite images help—but they cannot replace an engineer
Large-scale damage assessments often begin from above.
The UN Satellite Centre, known as UNOSAT, compares satellite imagery taken before and after destruction to identify structures that appear destroyed or damaged. This allows humanitarian organizations to map enormous areas where physical inspections are difficult or dangerous. UNOSAT’s work has been used to produce Gaza-wide damage assessments.
Remote sensing can answer questions such as:
- Is a building still standing?
- Has its roof collapsed?
- Has its footprint changed?
- Is there visible debris around it?
- Has the structure changed substantially compared with earlier imagery?
But satellite imagery generally cannot determine the full internal condition of a reinforced-concrete frame.
That distinction is important. “Damaged” on a satellite map is not synonymous with “unsafe to occupy,” and “standing” does not mean “safe.” Remote sensing is most useful for prioritizing inspections and understanding the scale and distribution of damage.
A typical assessment has different levels
There is no single universal procedure for every conflict zone or building. Assessment systems vary according to local authorities, engineering standards, available personnel and the urgency of the situation.
A useful way to understand the process is as a progression:
| Assessment stage | Main purpose | Typical decision |
|---|---|---|
| Remote assessment | Identify damaged or potentially dangerous structures across large areas | Prioritize buildings for inspection |
| Rapid visual inspection | Identify obvious hazards and signs of instability | Occupy, restrict access or refer for detailed assessment |
| Detailed structural assessment | Determine the condition of structural components and remaining capacity | Repair, stabilize, evacuate or demolish |
| Post-repair inspection | Verify that remedial work has restored adequate stability | Permit appropriate reoccupation or require further work |
The boundaries between these stages can overlap, particularly during an emergency.
Why Gaza presents an unusually difficult assessment problem
The engineering question is only part of the problem.
In an ordinary disaster, authorities might evacuate a damaged building, cordon it off, bring in structural engineers and begin repairs. Gaza’s housing shortage means that evacuation does not automatically produce a viable alternative.
The scale of destruction is enormous. The 2026 Gaza Rapid Damage and Needs Assessment by the World Bank, European Union and United Nations estimated hundreds of thousands of damaged or destroyed housing units and placed total recovery and reconstruction needs at $71.4 billion over a decade.
At the same time, engineers and emergency responders face access, equipment and safety constraints. The September 16, 2026 collapse of a previously damaged Gaza City apartment building illustrated the consequences: rescue workers had to search through rubble while facing shortages of heavy machinery and other equipment.
This creates a difficult distinction between identifying an unsafe building and being able to remove people from it.
What happens when a building is judged unsafe?
If inspectors determine that a structure poses a serious collapse risk, the normal safety response is to prevent people from entering or remaining inside it.
Depending on the damage, authorities may:
- restrict access;
- establish an exclusion zone around the building;
- relocate occupants;
- stabilize the structure where feasible;
- remove particularly dangerous components; or
- recommend demolition when repair or stabilization is not technically viable.
The appropriate response depends on the nature and severity of the structural damage.
For buildings that remain potentially repairable, emergency stabilization can sometimes be preferable to complete reconstruction. Engineering organizations have noted that rapid repairs to lightly or moderately damaged structures can provide housing more quickly than rebuilding entirely new homes.
Why a “safe” label is not necessarily permanent
Structural safety is not a one-time judgment in a changing environment.
New damage can occur. Previously hidden defects can become visible. Rainwater can enter damaged components. Nearby demolition or debris removal can affect unstable structures. And additional attacks or explosions can fundamentally change the assessment.
For that reason, a building that has passed an initial inspection can require reassessment if its condition changes.
This is also why emergency guidance tends to distinguish between temporary occupancy and a permanent declaration that a building is fully safe.
The International Emergency Shelter Cluster’s guidance for Gaza specifically provides households with basic visual checks for damaged buildings, illustrating the need for practical screening when professional inspections cannot immediately reach every structure.
The hardest decision is often not technical
In Gaza, the question facing authorities is frequently not simply, “Is this building safe?”
It is also: “If it is not safe, where can the people inside go?”
That second question can determine what happens in practice. A structural engineer may identify a genuine collapse hazard, but evacuation requires alternative shelter, transport, access to essential services and somewhere secure for displaced families to stay.
The result is a dangerous gap between engineering safety and real-world shelter availability.
The September 2026 collapse showed why that gap matters. Reports said the building had previously been damaged and was considered unstable, yet displaced families were living inside because safer housing options were severely limited.
What would make assessments more reliable?
For a damaged building to move from emergency screening toward safe reoccupation, several things have to happen together: qualified structural inspection, adequate access to the site, appropriate testing where necessary, removal or stabilization of dangerous elements, and sufficient construction materials for repairs.
The broader Gaza recovery assessment underscores the scale of that challenge. Rebuilding housing is not simply a matter of replacing roofs and windows; it requires restoring structural systems, infrastructure and basic services across an extensively damaged urban environment.
The immediate safety indicator is therefore not merely whether a damaged building remains standing. It is whether competent assessors have determined that its structural system is sufficiently stable and whether occupants have a genuinely safer alternative when it is not. Until both problems are addressed, the line between shelter and structural hazard will remain dangerously blurred for many families.