Managing Design Changes During Construction to Control Cost and Responsibility
Construction projects rarely proceed exactly as planned. Design changes during construction are common and often necessary. Yet, these changes can affect the project’s scope, cost, schedule, procurement, and responsibilities. Without a clear process, they can lead to disputes, delays, and cost overruns.
In this article, I explain how to manage design changes effectively in renovation, fit-out, or construction projects in Thailand. Following a formal change-control process helps keep projects on track and ensures all parties understand the impact before work proceeds.
Why Construction Changes Occur
Changes during construction happen for many reasons. Some common causes include:
Owner requests for modifications or upgrades
Design development revealing better solutions
Unforeseen site conditions such as hidden utilities or soil issues
New or updated authority requirements and regulations
Unavailability of specified materials or products
Contractor proposals for alternative methods or cost savings
Errors or omissions in original design documents
It is important to record the reason for each change clearly. This record should avoid assigning blame or legal responsibility prematurely. Understanding why a change is needed helps the project team evaluate its impact objectively.
Defining the Proposed Change Clearly
Before any pricing or instruction, the proposed change must be clearly defined. This includes:
The original design or requirement
The exact modification requested
The reason for the change
Drawings or documents affected
Any completed work impacted
The party requesting the change
Verbal requests should never be treated as approved instructions. All changes must be documented in writing to avoid misunderstandings later.
Reviewing the Technical Impact
The design team should assess how the change affects all technical aspects of the project. This includes architecture, structure, mechanical, electrical, plumbing (MEP) systems, finishes, furniture, and adjoining work.
Even minor changes can have significant technical consequences. For example, changing a wall location might affect structural supports or MEP routing. A thorough review ensures the change is feasible and identifies any additional design work required.
Assessing the Cost Impact
The contractor’s cost proposal for the change should detail:
Labour required
Materials and equipment needed
Demolition or removal of existing work
Waste disposal and logistics
Overhead and profit
The project team should review the basis of the price, including quantities and unit rates. Any uncertainty or assumptions should be clearly recorded. This transparency helps avoid disputes over cost later.
Assessing the Programme Impact
Changes can affect the project schedule in several ways:
Material lead times may increase
Completed activities might need rework
Subcontractor sequences could be disrupted
Practical completion dates may shift
The contractor’s proposal should separate the direct working time for the change from broader impacts on the overall construction programme. This distinction helps the project team understand the true schedule effect.
Identifying Responsibility Without Assumptions
The change record should clearly identify:
Who requested the change
Who prepared the revised design
Who reviews compliance with standards and regulations
Who approves the work
Responsibility depends on the contract terms and the specific facts of the change. Avoid assumptions or assigning blame without proper review.
Approval Before Work Proceeds
No change should proceed without clear approval status. Typical statuses include:
Proposed
Under review
Approved
Rejected
Even urgent work requires a recorded instruction defining the scope and cost basis. This protects all parties and ensures clarity.
Maintaining a Change Register
A change register is essential for tracking all design changes. It should include:
Unique reference number
Description of the change
Originator of the change
Cost status (proposed, approved, rejected)
Programme status
Final agreed value
Small changes can add up. Reporting the cumulative effect helps the owner and project team understand the overall impact.
Updating Project Records
Once a change is approved, all project documents must be updated. This includes:
Drawings and specifications
Cost plans and contract values
Inspection and testing requirements
A signed change order should never remain disconnected from site documents. Keeping records current avoids confusion during construction and handover.
Common Mistakes to Avoid
Some frequent errors in managing design changes include:
Instructing changes verbally without documentation
Starting work without a clear scope or cost agreement
Ignoring the impact on the project schedule
Failing to update project records and drawings
Treating contractor proposals as approved instructions
Avoiding these mistakes reduces risk and keeps the project on track.
Practical Change-Control Sequence
A reliable process for managing design changes includes these steps:
Identify and record the change request
Confirm the reason and gather required information
Review technical impacts with the design team
Obtain cost and programme impact details from the contractor
Clarify responsibility and approval authority
Approve, reject, or conditionally approve the change
Issue a controlled instruction to proceed
Monitor implementation on site
Update all project records and documents
10. Close the change with evidence of completion
Following this sequence ensures changes are managed transparently and efficiently.
Managing design changes effectively requires coordination between the owner, design team, and contractor. For example, services like design coordination, change-control administration, and cost-impact review can help streamline this process.
In Thailand, companies such as AD ASIA Consulting offer these services to support project teams. Their expertise in programme-impact review and construction management helps avoid costly delays and disputes. Engaging such specialists early can improve project outcomes.
Change is inevitable in construction. The key is to ensure every change is understood, authorised, priced, recorded, and integrated into the project. This approach protects budgets, schedules, and relationships.
If you are planning a renovation, fit-out, or construction project in Thailand, consider a professional Construction Change-Control Review before proceeding with design changes. This step can save time and money by clarifying impacts upfront.
Disclaimer: Design changes, contractual authority, valuation, time entitlement, engineering, and approval requirements must be reviewed for each project by qualified professionals. This article provides general guidance only.
By managing design changes carefully, projects can stay on course and deliver the expected results. Clear communication, thorough review, and proper documentation are essential. This ensures that changes add value rather than risk.
For more information on managing design changes and construction projects in Asia, visit AD ASIA Consulting.
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