Understanding ground conditions and how SuperSlab+ can benefit your residential build

The condition of the ground beneath your project is critical to foundation performance. Soil type can directly affect stability, making it essential to confirm that the site meets the required standards before construction begins.

Allied Concrete offer SuperSlab+, a foundation system designed for optimal performance on “good ground” conditions. 

What is “good ground”?

In accordance with NZS3604 and the New Zealand Building Code B1, "good ground" refers to soil that is stable, with a consistent bearing capacity, and minimal risk of movement or instability. For a foundation to work effectively, the ground beneath it must meet certain criteria, including:

1. Consistent bearing capacity: The ground must provide a solid foundation with uniform bearing strength.
2. Stable platform: The soil must be free from conditions that could cause vertical movement greater than 25mm over the lifespan of the building.
3. Slightly expansive soils: Minimal expansive soils ensure that the ground doesn’t shrink or swell with seasonal moisture changes, which can destabilise the foundation.
4. Imported fill: In cases where imported fill is used, it must be compacted correctly to create a stable foundation.

Not all sites meet this definition. For a full breakdown, including site-specific requirements and design considerations, refer to the Allied Concrete SuperSlab Technical Manual.

How SuperSlab+ helps

SuperSlab+ is ideal for “good ground” sites, delivering:

• Durability for long-term performance
• Energy Efficiency with a thermally efficient design
• Ease of Installation to save time on-site
• Sustainability through QPOD, low material waste, and Ecrete low-carbon concrete

If your site isn’t suitable

Not all sites will automatically meet the criteria for “good ground,” but that doesn’t mean SuperSlab+ is off the table. If your site has expansive soils or unstable conditions, specific engineering solutions can be implemented to ensure SuperSlab+ works for your project.

Allied Concrete always recommend obtaining a geotechnical report to assess the suitability of your site. If issues arise, a structural engineer can collaborate with a geotechnical engineer to adjust the design and ensure the foundation will perform as needed.

Why choose SuperSlab+?

Selecting the right foundation is key to stability and longevity. For projects on “good ground,” SuperSlab+ offers a proven, efficient, and sustainable solution — supported by Allied Concrete’s expertise and their DesignHub service to make the process seamless.