Even with the best planning, it is often necessary to make design revisions (Change Orders) or adjust details during the actual construction process. This could be due to encountering unexpected site conditions, changes in the owner's requirements, or improvements for better efficiency. However, these revisions or changes must be handled correctly according to the law and proper procedures to avoid legal violations, quality issues, budget overruns, and disputes with the designer or contractor.

8.1 Common Reasons for Design Revisions During Construction

Design revisions during construction often stem from various factors, including:

• Actual site conditions do not match the plans: e.g., discovering old piles, underground pipes, or soil layers that differ from the survey results.
• Changes in the owner's requirements: The owner may have a change of mind or desire additional functions.
• Improvements for efficiency: The architect or engineer may find a better construction method or a more suitable new material.
• Errors in the plans: There may be points in the design that were miscalculated or cannot be practically constructed.
• Budgetary issues: Some details may need to be scaled back to stay within the specified budget.

8.2 Types of Design Revisions According to the Law

Design revisions during construction are divided into two main types according to the regulations of the Building Control Act:

8.2.1 Revisions that Do Not Require a New Permit

Some revisions are not considered a "building modification" in the legal sense and can be carried out without applying for a new permit. It may only require notifying the local official, or it may not be necessary to notify at all, depending on the discretion of the designer and supervisor as to whether it qualifies as a minor change.

Minor changes include:

• Changing surface finishing materials for walls/floors/ceilings that do not affect the main structure.
• Changing the building's paint color.
• Changing the position of doors/windows without expanding the opening or affecting a load-bearing structure.
• Changing sanitary ware or non-structural building fixtures.

Best Practice: These changes should be recorded in the "As-Built Drawing" and approved by the supervising architect/engineer.

8.2.2 Revisions that Require a New "Building Modification" Permit

If the change qualifies as a "building modification" under the Building Control Act, B.E. 2522 (and ministerial regulations), a new building modification permit must be applied for and obtained from the local official before that part of the construction can proceed.

Characteristics that qualify as "building modification":

• Changing the area: Increasing, decreasing, or expanding the area of the building's structure.
• Changing the main structure: Such as columns, beams, foundations, floors, or the roof (if it is a load-bearing structure).
• Increasing/decreasing the number of floors, or changing the level of a floor.
• Changing structural walls or roofs, or walls/roofs that affect the stability of the building.
• Increasing the load-bearing capacity affects the main structure.
• Changing the building's use: From one type to another (e.g., from a house to a shop).

Steps to apply for a new modification permit:

1. Prepare new revised plans: The architect and engineer must sign and certify the revised part of the plan.
2. Prepare documents: Such as a copy of the title deed, ID card, the original construction permit, and the revised plans.
3. Submit an application form (Form Khor 1) for modification to the local official in the area where the building is located.
4. Wait for review: The local official will check the plans and consider them according to the law.
5. Pay the fee and receive the permit: Once approved, you can proceed with the construction of the revised part.

8.3 The Importance of "As-Built Drawings"

As-Built Drawings are a set of plans that reflect all the construction details as they happened on site, including every change and revision made during construction. They may differ from the original Construction Drawings used for the permit application.

Importance:

• Reference evidence: They are crucial evidence for the building owner for future maintenance, repairs, or modifications.
• Applying for a Certificate (Form Or.6): In some cases, the local official may request the As-Built Drawings to support the issuance of the Building Construction Certificate (Form Or.6).
• Problem-solving: They help in identifying the cause of problems if issues arise in the future.
• Responsibility: The contractor is usually responsible for preparing the As-Built Drawings, with the supervising architect and engineer verifying their accuracy.

8.4 Consequences of Not Handling Design Revisions Correctly

Neglecting to handle design revisions correctly can lead to major problems:

• Breaking the law: If a building is modified without a permit, you may be ordered to suspend construction, demolish the revised part, or be fined.
• Structural problems: Modifying a structure without an engineer's certification can result in an unstable and dangerous building.
• Disputes: Disputes may arise between the owner and the contractor or designer if there is no clear documentation of the changes.
• Project delays: Being ordered to suspend construction to wait for design revisions and a new permit will inevitably delay the project.
• Failure to obtain a Certificate (Form Or.6): If the constructed building does not match the permitted plans and was not revised correctly, you may not be issued a Building Construction Certificate (Form Or.6), which is necessary for house registration.

8.5 Scenario Example: Mid-Construction Changes to the "Dream House"

• Khun Ton and Khun Fon: A couple building their first modern-style home. Excitedly, they frequently visit the site to check on the construction progress.

Situation 1: A Minor Change (No new permit required)

• The Need: As the tilers are about to start on the master bathroom, Khun Fon sees a new, beautiful marble tile pattern in a magazine and feels it is much nicer than the one chosen in the original plan. She wants to change the tiles immediately.
• The Correct Procedure:
  
  1. Khun Fon and Khun Ton inform the supervising architect of their wish.
  2. The architect considers it and sees that changing the floor finishing material does not affect the main structure or the building's load capacity. He informs them that it can be done without applying for a new permit.
  3. The architect then instructs the contractor to change the material according to the owner's request and records this change to be included in the As-Built Drawing later.

Situation 2: A Change Affecting the Structure (Modification permit required)

• The Need: As the second-floor structure is nearing completion, Khun Ton feels the study room is too small. He has an idea to extend the study room's balcony by another 1.5 meters from the original plan to create space for a coffee table and some plants.
• The Correct Procedure:
  
  1. Khun Ton presents this idea to the architect and engineer.
  2. The structural engineer immediately inspects and explains that "extending the balcony is an increase and expansion of the building's structural area, which directly affects the original beams and floor." This falls under the legal definition of "building modification."
  3. The team must therefore halt construction on that specific balcony area (though work on other parts of the house can continue).
  4. The architect and engineer prepare a new revised plan for the extended balcony structure.
  5. They then take this new plan to submit a building modification permit application (Form Khor 1) to the municipality.
  6. Only after the modification permit is received can the contractor begin building the balcony according to the new plan.

Conclusion from the Scenarios: Khun Ton and Khun Fon learned that not all changes are the same. Some are simple updates that just need to be noted and recorded, while others are major issues that require work to be stopped to follow the legal procedures. The decision to consult their architect and engineer every time they wanted a change helped ensure their "dream house" was completed correctly, safely, and without legal problems.

8.6 Conclusion

Design revisions or changes during construction are things that can happen. But the important thing is to proceed with an understanding of the law. Consulting expert architects and engineers and strictly following the procedures for applying for a modification permit will help ensure that the change is legally correct, structurally safe, and does not cause problems later on.

References

• Building Control Act, B.E. 2522 (พระราชบัญญัติควบคุมอาคาร พ.ศ. 2522) and its relevant Ministerial Regulations.