The design process is the foundation of every construction project, but it is also a major source of costly mistakes. Lack of experience, time pressure, the erosion of mentoring culture, and insufficient training in new software tools all contribute to design errors that increase construction costs and the risk of delays. How can they be minimized?

The design process is the foundation of every construction project, but it is also a major source of costly mistakes. Lack of experience, time pressure, the erosion of mentoring culture, and insufficient training in new software tools all contribute to design errors that increase construction costs and the risk of delays. How can they be minimized?

The building design process is complex and inherently prone to error. While eliminating mistakes entirely is rarely possible, their impact on project budgets is significant. Numerous studies show that design documentation errors generate substantial increases in construction costs. In Australia, direct and indirect costs of design errors have been estimated at approximately 6.85% and 7.36% of contract value respectively (around 14% total). In the United Kingdom, design errors and omissions are reported to cost the construction industry billions of pounds annually, with frequent issues including uncoordinated, incomplete, unclear, delayed or simply incorrect designs.

The consequences extend beyond budget overruns. Design defects lead to rework, contractor claims, schedule delays, and in severe cases can compromise safety. Historically, design errors have been the root cause of numerous structural failures and building collapses.

Design errors stem from a variety of sources. Limited practical experience among young engineers, excessive time pressure, overreliance on technology, or lack of support from experienced mentors—all of which can substantially increase costs and complicate project delivery.

Limited experience of young engineers and its impact on design quality

One key factor behind the prevalence of design mistakes is the limited practical experience of junior engineers. In the past, it was standard practice for young engineers to gain on-site experience under the supervision of a mentor—learning through site inspections and direct exposure to construction processes. Today, however, many early-career engineers spend most of their time behind a screen, rarely visiting construction sites. The President of the Institution of Structural Engineers has noted that emerging generations of designers increasingly lack essential field exposure and practical structural awareness.

Insufficient contact with real-world construction conditions results in designs that are poorly adapted to site constraints or unrealistic in terms of construction feasibility. An experienced site engineer can foresee installation difficulties or execution risks—issues a novice designer may overlook without a “constructability filter”.

In practice, design often proceeds without meaningful contractor or constructability review. Cost pressure leads many clients to choose the cheapest design services and later pursue further “optimizations,” sometimes involving additional designers merely to endorse revisions. This model offers young engineers little opportunity to understand how their design decisions perform in real construction conditions.

Lack of such practical grounding eventually leads to issues in the design—ranging from minor clashes to major load underestimations or inadequate structural solutions, which then increase construction costs through corrective works, strengthening measures, or technology changes. Experts emphasize that many failures could be avoided if both design and execution were more frequently reviewed by experienced professionals, and if junior staff had regular exposure to construction sites.

Automation and BIM – improved quality or new challenges?

The growing automation of design processes was expected to reduce errors. Designers now use advanced CAD tools and Building Information Modelling (BIM), which facilitate multidisciplinary coordination. BIM enables the creation of a digital 3D model of the asset with all installations and components, allowing clashes and inconsistencies to be detected at the design stage. This significantly reduces-the risk that, for example, a ventilation duct collides with a floor beam or a pipeline intersects an electrical route—issues identified and corrected before reaching the construction site.

According to BIM coordinators, improved coordination through BIM directly translates into lower costs and fewer on-site errors. Automation also includes structural analysis software that generates calculations quickly, as well as tools for automatic drawing production.

However, technology is only a tool—its effectiveness depends on user competence and proper process organization. BIM requires accurate data input and close collaboration within the multidisciplinary project team. If an inexperienced designer relies too heavily on the software, they may overlook subtle execution-related issues that programs cannot resolve (e.g., buildability concerns such as installation sequence or equipment access). Automation reduces human calculation errors and simplifies clash detection, but it can also encourage complacency.

Moreover, not all errors can be captured digitally. A BIM model might fail to fully reflect complex physical behavior or non-standard materials if the designer does not introduce appropriate assumptions.

Therefore, new technologies cannot replace experience and engineering judgment. The optimal approach combines BIM capabilities with professional expertise—ensuring that automated outputs are buildable, compliant with engineering standards, and suited to real site conditions. Only this integration produces the quality outcomes the industry aims for.

Time pressure and the sacrifice of quality

Another major contributor to design errors is time pressure. Clients expect the design phase to be minimized, and contractors often demand documentation “immediately” to maintain aggressive schedules. In practice, this means designers work under unrealistic deadlines, leading to rushed outputs and incomplete checks. Design packages issued for tender or construction are often incomplete—sometimes based on concepts only 50% developed and finalized only during execution.

Experienced engineers describe such practices as irresponsible, even if they understand that young designers may feel unable to resist managerial pressure. Unfortunately, haste is the enemy of quality. Missed details and errors reappear later with amplified consequences.

When omissions or mistakes in drawings are discovered on-site, they cause work stoppages and require clarifications, redesign, and corrective action. Each clash identified in the field generates RFIs (Requests for Information), disrupts schedules, increases costs, and can affect overall quality.

Time pressure also drives last-minute design changes—a leading cause of defects according to industry research. As a result, documentation issued to site is often delayed and of lower quality than in previous decades. Surveys show that contractors consider the quality and timeliness of design information to be worse than at any point in recent history.

Unrealistic deadlines prevent proper internal checking and multidisciplinary coordination, shifting numerous errors to the construction site—where fixes are exponentially more expensive. Each week “saved” during design may result in months of delay during execution. Major project examples demonstrate that early haste leads to costly problems later; the Berlin Brandenburg Airport opened ten years late at triple the budget, partly due to severe planning and design errors and thousands of changes during construction.

Contractor-driven changes also contribute to design errors. When contractors propose cheaper alternatives without proper consultation, these modifications may compromise system performance, create clashes, or require expensive rework.

Investing in a robust design and realistic schedule is far cheaper than correcting errors produced by excessive time pressure.

The decline of traditional mentoring models

Historically, design offices followed a master-apprentice model: junior engineers learned under senior designers who corrected mistakes, explained structural principles, and gradually delegated responsibility. Today this form of mentoring has weakened significantly. Contributing factors include widespread retirements of experienced engineers, the lack of formal onboarding programs, and economic pressures that reduce time available for technical reviews.

As a result, a widening generational gap is evident. Universities provide strong theoretical foundations but cannot fully prepare graduates for the fast-paced, multidisciplinary design environment.

The absence of mentoring negatively affects design quality. Junior engineers—often without professional licenses and therefore not legally responsible for the design—may overlook technical nuances. This is a natural stage of development, but the problem arises when the supervising engineer does not thoroughly review the documentation before it is issued for construction.

In the past, multi-stage checking was common: the assistant prepared the design, the lead engineer reviewed it, and the chief designer provided final approval. Today, this review chain is often shortened or bypassed entirely, increasing the risk that errors go unnoticed.

The decline of mentoring and weakened design supervision also lead to the loss of “historical knowledge”—experience from past projects that once helped prevent repeated mistakes. Industry organizations now stress the importance of rebuilding knowledge-transfer frameworks through structured onboarding, junior–senior collaboration, dedicated review time, and formalized checking processes.

How to minimize design errors and their financial impact?

Experts recommend a combination of organizational and technical best practices, including:

• Establish mandatory design reviews (design reviews, internal and external audits).
  All documentation should be checked by a second designer or a dedicated review team before being issued for construction.
  Conduct regular multidisciplinary coordination meetings to identify collisions early.
• Make sure BIM models are continuously updated and shared with all project stakeholders.
  Use a Common Data Environment (CDE) to track revisions, comments and changes, reducing information chaos. Provide proper training so the team knows how to use BIM correctly and consistently.
• Avoid excessive time pressure that forces rushed work.When design changes are necessary, implement them in a controlled manner.Use a clear change-management protocol: each modification must undergo a formal assessment of its impact on cost, schedule and other disciplines. Clients should understand that “faster” does not mean “better” and that the cost of correcting mistakes far exceeds savings from compressing the design phase.
• Establish mentoring programs pairing junior engineers with experienced specialists. Involve designers in construction practice (e.g., site rotations, attendance at site meetings and inspections). Provide continuous training on up-to-date standards, new technologies and case studies of design failures to avoid repeating common mistakes.

Engage contractors early in the process (e.g., constructability reviews, design-for-construction sessions), so potential issues can be identified before design freeze.
Clients should clearly communicate project assumptions and respond promptly to designer questions.
Avoid information silos — fast clarification of issues reduces the number of incorrect assumptions.
Industry studies show that increased designer–client communication during the design phase leads to earlier detection of errors and cost-free corrections.