How to deal with Unauthorized Changes on Sites 

This article provides guidance on how structural engineers should handle the problem of unauthorized changes on construction sites.

Example of Engineers on site during a site inspection of unauthorized changes

Unauthorized changes on sites can be defined as a departure from the design specifications without any formal approval. Unauthorized changes on a construction site can lead to serious consequences. Not only can they compromise the safety of workers and the quality of the final outcomes, but they can also result in legal and financial liability against the accountable parties. Therefore, it is very crucial for construction managers, supervisors and entire team to take proactive measures to prevent and deal with unauthorized changes on sites.

Unauthorized changes on construction sites commonly arises from misrepresentation of the design. This often occur, either due to ambiguity, lack of clarity or absence of design for some particular elements or it could just be a failure on the part of implementation to consider it. Alternatively, an unauthorized change can simply be the result of some incorrect implementation of the design, either because it could not be constructed as designed on site or a deliberate change towards making the work easier, faster or cheaper to construct.  At other times it could simply the case of contractor fraud or attempts at deliberate concealment by unscrupulous timing of site inspections.

When unauthorized changes occur on construction sites, they give rise to a conflict of interest, particularly in design-built projects. They can compromise stability, durability, robustness, safety, repairability, maintainability, capital or whole-life cost, professional ethics (particularly where safety is compromised) and the requirements of other disciplines and approving authorities.

This article looks at problems of unauthorized changes on construction sites and provides guidance on how the structural engineer can proceed when they occur.

Initial Assessment

Once your notice is called upon or you’ve become aware that an unauthorized change has occurred on a site, the first step toward resolution is to assess the nature of the change to determine if the change could possibly cause danger to people’s health or the safety of the property itself. As an engineer or member of the larger team, you are duty bound to warn and this warning must be in strong and in very clear terms, irrespective of whether this change occurred within your scope of work or not.

Secondly, you must assess the implications of this change on the original specification. Can this change be resolved immediately? If yes, what are steps and if not, what are the implications? Regardless of whether this change can be resolved quickly or not, you are duty bound to advise the client and the other members of the construction team of the change towards determining what part of the contractual item it affects.

Thirdly, determine if there is a risk of a claim, arising from the unauthorized change been instituted against you. Where there is this risk, you should notify your professional indemnity insurer without delay. Engineers are warned to avoid assuming that an unauthorized change which appears to be the fault of another party on the surface will not develop into a claim against them (see cautionary tale 1). You must access your own information more critically, as during litigation, even the most ‘black and white’ situations could become grey.

Cautionary Tale 1

The contractor handling a new residential development, finds a non-existing column on the foundation drawing shown on the first-floor layout. After reviewing drawings, the contractor proceeded by assuming that this column was to start from foundation and soon after, commenced breaking of the oversite concrete. But, when the structural engineer visited site, he confirmed that the column wasn’t starting from the foundation level but from a beam on the first floor. Hence, the decision of the contractor to commence breaking the oversite concrete was an unauthorized change. However, when the drawing was reviewed, the structural engineer’s drawing was found to be ambiguous, and therefore he was partly held liable for the error.

Investigating the Unauthorized Change

The second step is to investigate the nature of the unauthorized change. While investigating, take detailed, dated and timed photographic and video evidence. Make written notes of all conversations that take place either in person or by phone as the chronology of events often becomes important later. Priorities reaching a solution but follow due process and resist pressure to cut corners to save time.

Where your contractual position permits, the site team should be notified immediately that an unauthorized change has occurred. Explain the unauthorized change with sensitivity and in a spirit of cooperation. Determine whether the site team agrees that an unauthorized change has occurred – this may even help to identify why it happened. All of these help in reaching a resolution as quick as possible, thereby saving everyone the time and effort.

After determining an unauthorized change, it might as well be worthwhile to consider the probability of this change having occurred elsewhere. When preparing proposals for remedial actions, the engineer should include any investigation as may be necessary to determine if this change affects other parts.

Cautionary Tale 2

An unauthorized change that doesn’t compromise your structural design can compromise the requirement the architect. For instance, in cautionary tale 1, introducing the unidentified columns from foundations meant that the column would not be hidden inside the wall but isolated inside one of the rooms at ground floor level thereby compromising the architectural design.

Drafting a Remedial Process

After assessing and investigating an unauthorized change, the next step is to prepare drafts of probable solution to the change. In preparing these drafts of remedial advice, you must prioritize your engagement with the entire team, in order to outline the implication of (1) not implementing any remedy. (2) implementing a remedy that reverts the change to its original specification. (3) Implementing a remedy that will improve the change but does not revert back to original specification.

It must be noted that remedial measures have to reasonable, an insistence on only an option that reverts an unauthorized change back to its original specification in most instances would be unlikely. However, it must be stated that attempts at the arriving at the best remedial solution must be made.

Albeit, that a remedy that falls short in terms of performance of the original design might be appropriate. However, such solutions often invoke an associated compensatory consideration. In other words, the impacts of the additional works and shortfall the remedy will have on all parties who did not contribute to the change must be compensated. Hence, brainstorming and sharing your observations and thoughts with the wider team is one very effective way of arriving at the best remedial solution, towards minimizing any compensation that might be made against you, in the event that you are liable.

In drafting your remedial options, the following should be included in your proposal:

  • The impacts of each remedial option on the original specification (for instance, reduced aesthetic appeal or poor durability)
  • Cost and programme implications.

Selecting a Remedial Solution

Once a preferred option has been selected from the drafts, as the engineer, you must now work to develop it in detail. The detailed proposal must be scrutinized by all members of the team to ensure that the selected proposal is not detrimental to designs made by other members of the team. A remedial scheme implemented without full consideration of other aspect of the total design can undermine other parts of the design leading to more serious issues (See Cautionary Tale 3).

Cautionary Tale 3

A structural innocuous unauthorized change occurred on a site in the form of a column being completely omitted. When the structural engineer sook to remedy the problem, he found that the column can be done away with. The remedy was a proposed 600mm deep beam as against the 450mm deep beam in the original design. All seemed okay, until the architect would kick against the solution, reasons been that it compromised the architectural requirement for headroom.

While developing a remedial specification, if you notice a significant departure in cost and timeline estimates compared to your draft, re-access the scheme. Once the scheme has been revised and other suggestions for additional investigation ready, share with the team, including the client for feedback. Finally, make any necessary changes and distribute the updated plan of work for written approval from the entire team.

Implementing the Remedial Solution

During implementation, ensure that you quickly carry out any proposed investigations and inspections of the remedial work. Failing in this regard, could result in a claim instituted against you should the project be delayed, where it has been found that you contributed to the unauthorized change.

Before any elements of the remedial scheme become hidden, you must inspect all implicated aspect thoroughly and keep detailed records, including photographic or video evidence and marked up drawings. You can use a sign-off system to identify what you have inspected and what aspect you have found to be satisfactory. 


Unauthorized changes on construction sites are a major source of concern with serious consequences for safety, quality and cost of project. As the saying goes -“prevention is better than cure.” hence the best way to deal with unauthorized changes is to stop them from occurring. Unauthorized changes can be difficult to nip in the bud when there is contractor fraud or deliberate concealment. However, when it’s the case of an error or ambiguity in design they can be very well avoided. The most effective ways of avoiding unauthorized changes are:

  1. Clear communication and regular monitoring
  2. Getting your design reviewed by a third party – issues that may constitute a case of unauthorized change on a site are better addressed at the conceptual design stage than during construction.
  3. Obtaining independent review of all site activities.

See: Engineering Ethics: Assumptions in Fee Proposals

Sources & Citations

Pitchers S. (2020) ‘Business Practice Note No. 35: Dealing with unauthorized changes on sites, The Structural Engineer, 98 (10), pp. 22–23. Institution of Structural Engineers

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