How Do I Build a Warehouse Without Sprinklers? 

If you're planning a warehouse or industrial building, you'll quickly run into the question: do I need sprinklers? For many business owners, the goal is to avoid them if possible. The cost of installing a sprinkler system can run into the hundreds of thousands — not to mention the ongoing maintenance, compliance, and water supply requirements. But is it always possible to design a warehouse without sprinklers? And if so, how?  

This article breaks down when sprinklers are required, when they can be avoided, and how the fire design of your building plays a critical role in that outcome.  

NOTE: The article does not address buildings that fall within the Hazardous Substances and New Organisms (HSNO) Act  

CONTENTS:

• Why Some Projects Aim To Design Out Sprinklers
• Sprinklers and the Building Code: Understanding C/AS2 and C/VM2  rl
• Designing Out Sprinklers: Practical Considerations  
• What Should I Confirm with a Fire Engineer?

Why some projects aim to design out sprinklers

Sprinklers aren’t always necessary in commercial or industrial buildings. In fact, many warehouse owners try to design them out. The reasons are practical:  

• Cost: Sprinkler systems can cost upwards of $500,000 to install.  

• Maintenance: They require an annual Building Warrant of Fitness (BWOF) and regular inspections.  

• Water supply: If onsite pressure is insufficient, you may need large, dedicated storage tank(s) — often over 100,000L — which brings further design and cost implications.  

In high-staffed, customer-facing environments like bulk retail (e.g. Bunnings), sprinklers make sense. They can reduce insurance costs and improve fire safety where more lives may be at risk. But in low-occupancy warehouses or manufacturing spaces, especially those used for storage only, sprinklers may not be necessary if the building is designed strategically.  

Sprinklers and the Building Code: Understanding C/AS2 and C/VM2  rl

For compliance with the building code, there are two key fire compliance paths in New Zealand:  

1. C/AS2 – the Acceptable Solution. A prescriptive path with defined rules for fire safety based on building use, height, and size.  

1. C/VM2 – the Verification Method. An engineered solution where a chartered fire engineer models how a fire would behave in your building, proving compliance through calculations.  

C/AS2 is simpler, faster and cheaper (around $4k), while C/VM2 is more complex and costly (typically $30k–$50k), but allows more design flexibility — especially when you want to avoid sprinklers.  

When Are Sprinklers Required Under C/AS2?  

In warehouses and industrial buildings, fire risk groups under C/AS2 matter. Most warehouse or industrial buildings fall into one of two risk groups:  

• WB (Business, industrial, commercial, low-level storage)  

• WS (High-level storage or fast fire growth risk)  

If your building falls into WS, sprinklers are generally required.  

Here’s when that happens:  

• Apex height is over 8m  or 

• Storage (e.g. pallet racking) exceeds 5m  and 

• Building footprint exceeds 4,200m²  

The first two above are the primary triggers for the WS risk group — which has a requirement for sprinklers under C/AS2.  

How to Stay Within WB and Avoid Sprinklers  

• If you want to avoid sprinklers in a storage building using the Acceptable Solution method (C/AS2), your design must stay within the WB risk group parameters: a floor area up to 4200m², an apex height no more than 8m, and storage heights that can exceed 5m.Keep the apex height to no greater than 8.0m  and;
• Keep the building footprint under 4,200m²  or;

• The building is to be ‘capable of storage’ to no more than 5.0m height. 

By doing this, you stay within the WB risk group and avoid triggering the stricter WS requirements.  

NOTE: Temperature controlled storage buildings have different criteria as do ‘Industrial activities’ buildings. 

Can You Still Avoid Sprinklers if You Exceed Those Limits?  

Yes — this is where C/VM2 comes in.  

Using the Verification Method, a fire engineer can model the spread of fire and smoke within your building. They calculate how quickly a fire would grow, how long it would take for the space to fill with smoke, and how much time occupants would have to escape.  

If the model shows people can evacuate safely without a sprinkler system, it can be approved by council. This method is more expensive and takes longer as it involves liaising with Fire Service as part of the initial fire report development (3+ months), but it often pays off by saving you the cost and complexity of installing sprinklers.  

Designing Out Sprinklers: Practical Considerations  

Designing out sprinklers isn’t just about ticking a box. Here are other factors to keep in mind:  

• Insurance: Some insurers may prefer sprinklers or offer better terms if they’re included.  

• Occupant risk: The more people in the space, the more caution is advised.  

• Usage: Manufacturing or warehousing typically carries lower human risk than retail.  

• Water pressure: If you do need sprinklers, can your site supply the required pressure? If not, you may need a large tank — often a tank over 100,000L — which must be placed onsite.  This can require a large amount of space on the site.

What Should I Confirm with a Fire Engineer?

Before finalising your design or choosing your compliance pathway, it’s worth getting expert input. For this article, we spoke with Fire Engineer Carol Caldwell, who helped answer some of the most common questions clients face when weighing up whether or not to include sprinklers. 

Here are the key considerations Carol raised:

When would it not be a good idea to design sprinklers out?  

Sometimes it comes down to insurance requirements, or a client’s desire to protect business continuity in the event of a fire.

Are there types of projects where sprinklers can’t be avoided, even with a verified method? 

Yes, Resource Consent conditions related to water supply can still trigger a need for sprinklers, regardless of fire engineering. 

What role does Resource Consent play in sprinkler requirements? 

Even if your fire design meets the Acceptable Solution or Verification Method, councils can still require sprinklers based on local firefighting water supply criteria (e.g. pressure and flow rates). This sits outside the Building Code but can heavily influence design. 

What practical or regulatory issues do clients often overlook?

Resource Consent water supply issues are frequently missed until late in the process.

Any changes in interpretation or trends recently?  

Fire and Emergency NZ is currently updating the Code of Practice for Firefighting Water Supply, which could affect how requirements are interpreted going forward. 

Related Reading  

• Fire Protection Regulations for Early Planning
• Common Questions and Misunderstandings About Fire Regulations