Project Management: How Design Changes Affect Cost and Delivery

Great designs on a blueprint may not always hold up well in reality. Take for instance the London building nicknamed “Walkie Talkie.” Even after it was finished, modifications had to be made to prevent the building’s concave mirror effect. When the sun hit the building, it damaged cars on the street. A permanent awning was installed to correct the flaw. No construction is immune from alterations and, as a result, delays and cost overruns can plague a project. The inclusion of a project management consultant in traditional or design-build delivery will help mitigate the risks associated with changes, which are almost guaranteed in any project. Why are design changes necessary halfway to completion? Should all changes be implemented? How can these unplanned activities be reduced if not eliminated?

Why Design Changes Occur

The first step to taking greater control of your commercial or residential project is knowing why an issue arises. Two factors classify changes in design: internal and external.

  • Internal factors include the client, the contractor, designer or consultant.
  • External factors involve environmental, political, economic or technological influences.

Client requests typically have the greatest influence when it comes to design modifications. A client may change their mind about the location of a room (instead of a guest room facing south, they now want it to face west) or decide that an infinity pool on the roof would add value to the property. In either case, the project team must discuss how the changes will affect construction and occupant safety.

01. Client-Induced Changes

Clients may change their minds about a project, altering the original scope of work. These changes may arise from a change in vision, a desire for added functionality, or new inspiration seen in other projects.

For instance, a client might decide mid-construction that they prefer a different layout or additional features like a smart home system. Such alterations often necessitate redesign, procurement of different materials and additional labour, all contributing to increased costs and extended timelines.

  • Cost: Budget will increase due to design fees, additional materials and labour costs.
  • Delivery: Delays will happen due to redesign and rework, extended project timelines.

02. Regulatory Changes

Regulations can change during a project’s lifespan, necessitating modifications to ensure compliance. These changes might involve new building codes, safety standards or environmental regulations.

As with other changes, regulatory updates can also impact cost and delivery.

  • Cost: Increase in budget is likely due to the need for redesign and compliance measures.
  • Delivery: Potential delays as plans are revised and approved by regulatory bodies.

03. Unforeseen Site Conditions

Unexpected conditions discovered during construction, such as poor soil quality, hidden contamination or archaeological finds, can prompt design changes. These unforeseen issues require immediate attention to avoid compromising the project, and minimising its effects on cost and delivery.

  • Cost: Budget may increase due to the need for additional materials, labour and possibly specialised solutions.
  • Delivery: Project may be delayed as the site is assessed and necessary modifications are made.

04. Technological Advancements

Advancements in technology can influence a project design, especially if new materials or construction methods become available. A project started several years ago might benefit from incorporating the latest sustainable materials or smart building technologies.

The effect of technological innovations on cost and delivery may look something like:

  • Cost: Potential increase in budget due to the availability of new materials and technology integration.
  • Delivery: Delays are possible to incorporate new technology, though recent improvements can sometimes expedite subsequent stages of construction.

05. Errors and Omissions

Mistakes in the initial design or overlooked details can necessitate changes once construction begins. These errors can stem from miscommunication, incorrect assumptions or simple human error. Their effect on cost and delivery may be substantial, depending on the scale of the error or oversight.

  • Cost: The budget will increase due to the need for corrections and additional materials.
  • Delivery: Deadlines will be pushed back as errors are identified and corrected, which may also require the re-approval of plans.

Mitigating the Impact of Design Changes

To minimise the impact of design changes on your project, consider the following:

01. Thorough Planning

Detailed planning at the project’s outset can help identify potential issues before they arise. Engaging all stakeholders early and ensuring clear communication can mitigate many changes driven by oversight or miscommunication. All of this can be facilitated by the right project management services.

02. Flexible Design Approach

Adopting a flexible design approach allows for the easier incorporation of changes. Modular design, for example, can accommodate alterations without significant rework.

03. Regular Communication and Stakeholder Engagement

Maintaining open lines of communication between all stakeholders can help catch potential issues early. Regular meetings and updates ensure everyone’s expectations are aligned and provide opportunities for feedback before changes become critical, allowing the team to promptly address concerns.

04. Change Control Process

Implementing a robust change control process helps manage modifications systematically. The process includes evaluating the impact of changes on cost and schedule before approval, ensuring that only necessary changes are made.

05. Use of Technology

Leveraging technology such as building information modelling (BIM) can help teams visualise the impact of changes before they are implemented. The software can reduce errors and facilitate better decision-making.

06. Proactive Risk Management

Conducting thorough risk assessments at the beginning of a project can help anticipate potential issues that may require design changes. Identifying these risks early on allows for the development of mitigation strategies and contingency plans, which can reduce the likelihood of costly and time-consuming changes later on.

You can also analyse previous projects. Review which areas required design changes that led to delays or cost overruns.

Manage Unplanned Changes

A visionary idea is the beginning of every building project. But sometimes, that idea still needs to be fully realised even when the permits have come in and experts are ready to turn that idea into reality. As a result, deviations from the design must be evaluated.

Design changes are an inevitable part of any construction project. Although they can lead to increased costs and delays, understanding the reasons behind these changes and implementing strategies can help mitigate their impact. Navigate the complexities of design changes and deliver successful projects with a well thought-out plan.


Design changes are an inevitable part of any construction project. While they can lead to increased costs and delays, understanding the reasons behind these changes and implementing strategic management approaches can significantly mitigate their impact. With thorough planning, flexible design approaches, regular communication, and proactive risk management, project  management teams can navigate the complexities of design changes and deliver successful projects that meet both budgetary and scheduling goals.

Also Read : How To Plan Your Workforce For Your Next Home Renovation

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