How Much Does a Concrete Floor Cost for a Shed in New Zealand?

If you are planning to build a workshop or storage shed, you will almost always need a concrete floor. One of the first questions people ask is what thickness of floor is required and what the overall cost will be. 

In short, you’ll almost always need a concrete floor, and in New Zealand, most non-structural shed slabs cost between about $110 + GST and $130 + GST per square metre (for 100 mm to 150 mm thickness on a prepared base). 

Structural slabs - which need engineering, perimeter thickening, and extra reinforcing - usually add at least 25% more to the price.

This guide explains the main types of concrete floors used for sheds in NZ, the most common slab thicknesses, and the average concrete cost per square metre.

Structural vs Non-Structural Concrete Floors

There are two main types of shed floors: structural slabs and non-structural slabs. The choice depends on the design of your shed and whether the concrete floor is required to support the building.

Structural Concrete Floor

A structural concrete slab is required for any building that bolts or attaches directly to the floor. In these cases, the slab is engineered to take the weight of the building and act as part of the foundation system. Steel sheds, whether roll-form steel or structural steel, generally need this type of slab before construction begins.

Structural concrete slabs cost more than non-structural slabs because they require engineering, additional earthworks, perimeter thickening, and more reinforcing steel. A trench is often excavated around the perimeter to create a concrete nib wall, which must be poured first.

Extra steel reinforcing connects the nib wall to the slab, and this process adds both time and material costs. Once the nib wall is complete, polythene and mesh are laid and tied into the reinforcing before the main slab is poured. The extra concrete and labour make the concrete slab foundation cost higher than simpler alternatives.

Non-Structural Concrete Floor 

A non-structural floor does not carry the load of the building. These are common in pole sheds where the poles themselves are set into the ground, leaving the floor free of structural requirements.

Pouring a non-structural slab is straightforward: boxing is attached around the poles, a layer of polythene is added, mesh is laid, and then the concrete is poured. With no perimeter thickenings or complex reinforcing needed, the preparation and labour time are reduced, which makes the cost per cubic meter of concrete used in these floors more affordable.

For sheds, this is usually the most practical and economical option.

How much does a concrete floor cost? 

A concrete slab for sheds is usually priced by thickness and by square metre.

• 100mm non-structural floor: Suitable for most general sheds, cars, and medium-sized tractors. The average concrete price per m3 in NZ works out to around $110 + GST per square metre, including mesh, polythene, and labour (assuming a flat, compacted gravel pad is supplied).
  
  
• 150mm non-structural floor: Recommended for truck storage or heavier equipment. These require heavier mesh and more concrete per cubic metre. Costs are typically around $130 + GST per square metre on a prepared base.
  
  

A non-structural slab is the simplest and most cost-effective option, while a structural slab can cost at least 25% more depending on shed size, soil preparation, and design requirements.

If you are comparing options, using this concrete cost calculator NZ can help you estimate your budget based on slab size and thickness.

Preparing Your Shed Site

Before any slab is poured, it’s important to ensure the site is well prepared with compacted gravel. This reduces long-term maintenance and ensures the slab performs as expected.

If you are exploring options for shed construction or looking for a more detailed concrete floor cost estimate, speaking with an experienced builder, or the team at Alpine, will help you understand the best slab design for your needs.

Build Your Shed with Confidence

Whether you choose a structural or non-structural slab, knowing the typical costs per cubic metre and per square metre will make planning your project easier. Concrete remains the most durable and cost-effective flooring solution for sheds in New Zealand.

If you are ready to start your project, get in touch with the team at Alpine. We can help you plan, design, and build a shed that fits your needs and budget.