This article argues that routine structural overdesign is not a safety net. It is a symptom of deeper issues within modern practice. While conservatism has its place in specific, high-risk scenarios, its widespread and uncritical application undermines the very principles engineers claim to protect.
Safety is the moral foundation of structural engineering. Every calculation, drawing, and specification ultimately serves the goal of protecting life. Yet within that noble objective lies a growing contradiction. Across the industry, many structures are designed far beyond what governing codes require, not because risk demands it, but because uncertainty, fear, and habit quietly dictate decision-making. Structural overdesigning has become so common that it is rarely questioned. In fact, in some quarters, you are at risk of your design been trashed, regardless of what your calculations show if you don’t overdesign. This is often praised as caution, excused as professionalism, and defended as good practice. In reality, it deserves far more scrutiny than it currently receives.
Overdesign presents itself as harmless. After all, a structure that is “too strong” will not collapse. However, this simplistic logic ignores the wider consequences of engineering decisions. Engineering is not only about preventing failure; it is about delivering safety efficiently, responsibly, and proportionately. When excess material replaces sound judgement, engineering drifts away from optimisation and towards defensive design. This shift matters, not just technically, but ethically, economically, and environmentally.
This article argues that routine structural overdesign is not a safety net. It is a symptom of deeper issues within modern practice. While conservatism has its place in specific, high-risk scenarios, its widespread and uncritical application undermines the very principles engineers claim to protect. Overdesign often signals discomfort with uncertainty, lack of confidence in analysis, or fear of accountability. None of these should define a mature profession.
Defining Structural Overdesign Beyond the Simplistic View
Structural overdesign is commonly misunderstood as merely “extra strength.” In reality, it is the persistent use of member sizes, reinforcement quantities, or material strengths that significantly exceed those justified by code-compliant analysis, without a clear, rational basis tied to risk or performance. Modern design standards already embed conservatism. Partial safety factors for actions and materials, load combination rules, robustness provisions, and serviceability limits exist precisely to address uncertainty. These factors of safeties are far generous. When engineers add further unquantified margins on top of these systems, they move beyond design and into assumption and guess work.
Overdesign manifests in many subtle ways. It appears in beams detailed with reinforcement far above required utilisation. It shows up in columns sized for loads they will never experience. It hides in foundation designs driven by extremely pessimistic soil assumptions that are never revisited. Each individual decision may seem minor. Combined across an entire structure, the result is a building that consumes more material, costs more money, and delivers little additional safety.
The most troubling aspect is that overdesign often lacks transparency. Engineers rarely document why they chose to exceed requirements. The decision is implicit rather than justified. This makes it difficult to distinguish between informed conservatism and unexamined habit. Over time, this ambiguity becomes normalised, and excess becomes embedded as “standard practice.”
Why Overdesign Has Become Normalised in Practice
Overdesign rarely begins with negligence. It begins with uncertainty. Structural engineers operate in an environment where data is incomplete, construction quality varies, and future use can change. Faced with these unknowns, many designers respond emotionally rather than analytically. Adding material feels like control. It creates a sense of protection against unknown outcomes, even when that protection is illusory.
Fear of liability plays an equally powerful role. Engineers work under intense professional pressure. Failures attract scrutiny, litigation, and reputational damage. Success, by contrast, is invisible. A structure that stands quietly for fifty years generates no headlines. This imbalance encourages defensive behaviour. Overdesign becomes a shield, not against structural failure, but against blame. The irony is that this behaviour reflects insecurity rather than competence.
However, this writer holds the firm view that uncertainty not envisaged by the code of practice cannot be engineered away. Design standards already account for variability, construction tolerance, and reasonable human error. They do not, and cannot, compensate for negligence, indifference, or greed.
No amount of writing of design codes and writing of contracts can in the end be guaranteed to prevent the results of stupidity, carelessness or incompetence. But one can do a great deal to discourage these vices and that must be done.” – Sir Alec Merrison
If a design properly requires 16 mm reinforcement and clearly specifies it, structural safety does not improve by inflating the specification to 20 mm “just in case.” A contractor willing to substitute 14 mm bars will do so regardless of what appears on the drawings. Overdesign does not correct misconduct; it merely disguises it on paper. Engineering is not a moral safety net for bad behaviour, nor should it pretend to be.
The False Comfort of “More Material Equals More Safety”
One of the most persistent myths in structural engineering is that additional material automatically increases safety. In reality, safety is about behaviour, not bulk. Many failure mechanisms are insensitive to member size. Progressive collapse, connection failure, fatigue, corrosion, and detailing errors are not solved by thicker sections. In some cases, overdesign can in fact worsen performance by increasing stiffness, mass, or force demand elsewhere in the structure.
Overdesigned structures can also mask poor understanding. When engineers rely on excess capacity, they may avoid engaging fully with load paths, second-order effects, or construction stages. This avoidance creates blind spots. A design that “works” because it is heavy may still be poorly understood. True safety comes from knowing how a structure behaves under real conditions, not from hoping that surplus strength compensates for uncertainty.
The danger lies in complacency. Overdesign can create a false sense of security that discourages rigorous checking, peer review, and optimisation. Engineers may assume that because members are large, risks are low. This mindset erodes analytical discipline, which is the real foundation of safety.
Economic Consequences Hidden in Plain Sight
One of the pillars of structural engineering is economy. A design must not be seen only be safe but also economical. And economy is in fact just as important as safety. A brief can be trashed on account of being to expensive to construct.
Therefore, the economic impact of overdesign extends far beyond material quantities. Additional concrete and steel increase self-weight, which drives larger foundations, stronger connections, and heavier lifting equipment. Construction programmes lengthen as handling becomes more complex. Transport costs may rise. Labour requirements also increase. None of these effects appear in isolation. They cascade through the project.
Clients often absorb these costs without realising their origin. They see higher budgets but assume they are unavoidable. In public projects, the consequences are even more serious. Overdesign consumes public funds that could support other infrastructure needs. It reduces value rather than enhancing it.
Engineering is fundamentally about efficiency. Delivering a structure that meets performance requirements with minimal waste is not optional. It is a core obligation. When engineers consistently overdesign, they fail to meet this obligation, even if no immediate harm occurs.
Environmental Responsibility and the Carbon Cost of Excess
The environmental implications of overdesign are no longer secondary concerns. Cement and steel production are among the largest contributors to global carbon emissions. Every unnecessary cubic metre of concrete represents avoidable environmental damage embedded in a structure for decades.
Overdesign directly contradicts sustainable construction principles. It increases embodied carbon without proportional benefit. It undermines efforts to decarbonise the built environment. Engineers who continue to design excessively must confront the reality that they are contributing to climate impact through avoidable decisions.
Sustainability is not achieved through certifications alone. It is achieved through restraint, optimisation, and informed judgement. In this context, overdesign is not conservative. It is irresponsible.
Professional Ethics, Accountability, and Engineering Identity
Engineering ethics demand balance. Safety must coexist with economy, durability, and societal responsibility. Overdesign disrupts this balance. It signals either a lack of confidence in one’s own analysis or an unwillingness to take responsibility for decisions. Neither reflects professional maturity.
While over-design may feel safe for the individual engineer, it weakens the profession as a whole. It normalises inefficiency and lowers expectations. It shifts engineering identity away from problem-solving and towards risk avoidance. Clients do not need engineers who simply add material. They need engineers who understand, justify, and optimise.
True accountability means standing behind a design that is sufficient, not excessive. It means being able to explain why a structure is safe, not just why it is strong.
When Conservatism Is Justified and When It Is Not
There are scenarios where higher margins are appropriate. Critical infrastructure, extreme hazard zones, and structures with severe consequences of failure demand enhanced reliability. In these cases, increased conservatism is driven by risk analysis, not fear. It is documented, justified, and proportionate.
The problem arises when this mindset is applied indiscriminately. Not every building is critical infrastructure. Treating ordinary structures as exceptional cases reflects poor judgement, not caution. Engineering requires differentiation. Without it, conservatism becomes waste.
Also See: [Viewpoint] The Decline of Structural Behaviour Knowledge – A Concerning Trend
Conclusion: Overdesign Is Not a Virtue
Structural overdesign may protect a building, but it damages engineering judgement. It replaces understanding with excess and confidence with fear. Safety is not achieved by doing more than necessary. It is achieved by doing exactly what is required, for the right reasons, and being accountable for those decisions.
If engineering is to remain a respected profession, it must reject the quiet normalisation of overdesign. Precision, restraint, and responsibility must once again define what it means to design safely.
