What is a Class 2 Building? Structural Design & DBP Compliance Explained
13 June 2025What is a Class 2 Building and Why It Matters for Structural Design
When it comes to residential construction in New South Wales, not all buildings are created equal—especially when it comes to compliance. At Stride Consulting Engineers, we frequently work on Class 2 buildings, which are unique in their requirements, risks, and responsibilities.
What is a Class 2 Building?
Under the National Construction Code (NCC), a Class 2 building is a residential apartment building where people live above and below each other. Think of multi-storey apartments, duplexes, or mixed-use developments with a residential component. These buildings are subject to strict regulation, particularly under the Design and Building Practitioners (DBP) Act 2020, to protect homeowners and increase accountability in the industry.
Challenges with Structural Design
Designing Class 2 buildings is more complex than designing single dwellings. Structural challenges include:
- Load distribution: Ensuring safe transfer of loads across multiple floors
- Lateral stability: Designing for wind and seismic forces, especially in coastal or high-risk zones
- Fire separation: Creating compliant fire-rated walls and floors between units
- Deflection control: Minimising movement in floors and walls that could affect finishes and resident comfort
- Construction sequencing: Managing structural staging to support safe and efficient construction
Why DBP Registration is Crucial
The DBP Act requires that all regulated designs for Class 2 buildings (like structural, civil, and stormwater) be carried out by registered Design Practitioners. This ensures that:
- The designs are safe, code-compliant, and fit for purpose
- They are lodged through the NSW Planning Portal before construction starts
- The practitioner is accountable for the quality of their work
At Stride, all our engineers working on Class 2 projects are registered under the DBP Act, meaning clients can trust that our designs meet the highest standards of safety and compliance.
Key Takeaways
- Class 2 buildings involve multi-unit residential living and require more complex design considerations.
- Structural design for these buildings must address stability, safety, and occupant comfort.
- Only registered engineers under the DBP Act can legally prepare and declare regulated designs for Class 2 buildings in NSW.
- Working with a DBP-accredited firm like Stride Consulting Engineers reduces risk, improves build quality, and ensures smoother project delivery.
Need help with a Class 2 development?
Contact Stride Consulting Engineers to ensure your project is structurally sound, compliant, and in capable hands.