Can you change brick types after your plan has been approved?

In the construction industry, "on-the-fly" changes are common. You might start with a plan for a traditional double-skin Imperial brick wall (230mm), but as the budget tightens, the cost-efficiency of Maxi bricks (180mm or 190mm) becomes hard to ignore.

From an estimating perspective, the savings on mortar and labor look great on paper. However, before you swap your order at the brickyard, you need to understand the legal and structural "red tape" involved.

The Short Answer: No (Not without a paper trail)

Under Section 4 of the National Building Regulations and Building Standards Act (Act 103 of 1977), you are legally required to build according to the approved plans and specifications.

Because a change from a 230mm wall to a 180mm wall is a material deviation affecting the structural thickness of the building, you cannot simply "just build it." Doing so without formal notification is a violation of the Act.

Why the Change Triggers a Legal Issue

When the municipality approves a plan, they aren't just looking at the room layout; they are approving a structural system.

• Structural Integrity (SANS 10400-K): A 230mm Imperial wall is a "double-skin" system that is generally "Deemed-to-Satisfy" (automatically accepted as stable). A 180mm Maxi wall is a "single-skin" system. Depending on the height of the wall and the weight of your roof, a 180mm wall may require a Rational Design, a formal certificate signed by a structural engineer proving the wall won't buckle.

  
  

• The Foundation Footing: Foundations are designed based on the weight and center-point of the wall above them. Changing the wall thickness shifts the "load path." If your foundation was poured for a 230mm wall and you place a 180mm wall on it, the weight might not sit centrally, potentially leading to structural cracks later.

  
  

• Council "Bulk" and Floor Area: Moving from a 230mm exterior wall to a 180mm wall actually increases the internal floor area of your house. In some municipalities, this change in "Bulk" (Floor Area Ratio) requires a re-calculation to ensure you haven't exceeded the legal limit for your property size.

  
  

The Risk of Building Without Approval

If you decide to "stealth" the change and hope no one notices, you face three major risks:

1. Site Stoppage: A municipal building inspector has the power to issue a Cease Works Order the moment they see Maxi bricks on a site approved for Imperial bricks.

   
   

2. No Occupancy Certificate: At the end of the project, you need a Section 14 Certificate of Occupancy to legally live in or sell the house. If the "As-Built" structure doesn't match the plan, the council will refuse the certificate.

   
   

3. Insurance Failure: If a structural issue occurs years down the line, an insurance company may check the approved plans. If the building doesn't match the specs, they may have legal grounds to void your claim.

   
   

The Professional Way Forward: "Amended Plans"

The good news is that you don't usually have to start the 6-month approval process from scratch. Most South African councils allow for Amended Plans (also called Deviation Plans).

• Step 1: Have your architectural professional update the drawings to reflect the 180mm wall thickness.

  
  

• Step 2: Obtain a Form 2 (SANS 10400-A) from a structural engineer. They will verify that the thinner wall can safely support your roof.

  
  

• Step 3: Submit these as "Amended Plans" to the local authority.

  
  

The Bottom Line

While Maxi bricks offer excellent value in an estimate, the "cost" of the brick isn't just the price per thousand. You must factor in the cost of updated engineering certificates and council submission fees.