Firestopping is the process of sealing penetrations — the holes made when cables, pipes, conduits and HVAC ducts pass through fire-rated walls, floors and ceilings — so that fire and smoke cannot travel through those gaps from one part of a building to another. In New Zealand, firestopping is a critical part of passive fire protection and is governed by the NZ Building Code, particularly Clause C (Protection from Fire), which sets out requirements for containing fire within a building and protecting escape routes.
Why Firestopping Matters
When a fire-rated wall or floor is built, it is designed to hold back fire for a set period — commonly 30, 60, 90 or 120 minutes — giving occupants time to escape and firefighters time to respond. Every time a cable tray, pipe or duct punches through that barrier, the fire rating is compromised unless the penetration is properly sealed. Without firestopping, fire and toxic smoke can race through service voids and cavities far faster than most people expect, turning a contained incident into a building-wide emergency.
Fire and Emergency New Zealand (FENZ) and MBIE Building Performance both emphasise that passive fire protection — including firestopping — is just as important as active systems like sprinklers and alarms.
What Gets Firestopped?
Any service that penetrates a fire-rated element needs to be assessed and, where required, firestopped. Common examples include:
- Electrical cables and cable trays passing through fire-rated walls or floors
- Plastic and metal pipes (water supply, drainage, gas, refrigerant lines)
- HVAC ducts and flexible connections — these can act like chimneys if not properly sealed or fitted with fire dampers
- Conduits (empty or filled)
- Structural joints and construction gaps between fire-rated elements
The challenge with plastic pipes is that they can melt and leave an open hole; intumescent collars (which expand rapidly in heat to close the gap) are typically used around these. Metal pipes conduct heat and may need intumescent wraps or pillows. Cable penetrations are often sealed with intumescent putty, blocks or mortar-based systems.
Common Firestopping Products Used in NZ
| Penetration type | Typical firestopping solution |
|---|---|
| Plastic pipes (PVC, PE) | Intumescent collar or wrap |
| Metal pipes | Fire-rated sealant, wrap or collar |
| Electrical cables/trays | Intumescent putty pads, blocks or pillows |
| HVAC ducts | Fire damper + intumescent sealant at perimeter |
| Construction joints | Fire-rated backing rod and sealant |
Well-known suppliers with products available in NZ include Sika and Ardex, both of which offer fire-rated sealant and firestopping systems. Always use a system that has been tested and assessed to the relevant NZ Standard for the specific penetration type — your fire protection specialist can confirm which standard applies. Products must be installed strictly in accordance with the manufacturer's tested system; mixing components from different systems can void the fire rating.
The NZ Regulatory Picture
For most commercial, industrial and multi-unit residential buildings, firestopping forms part of the building's compliance schedule as a specified system. This means:
- It must be inspected and maintained at intervals set out in the compliance schedule
- An Independent Qualified Person (IQP), registered with the local council (territorial authority), must inspect and certify the work using the relevant Form 12A
- The building owner must supply an annual Building Warrant of Fitness (BWOF) to the council, confirming all specified systems — including passive fire protection — are performing as required
For new buildings or alterations, firestopping work must comply with the Building Code and will generally require a building consent. Always check with your local council before starting work — some minor work may fall under Schedule 1 exemptions, but penetrations in fire-rated elements almost always require consent. Guidance is available from MBIE Building Performance.
For standalone residential homes, the rules are less prescriptive, but fire-rated construction (such as between an attached garage and the house) still requires penetrations to be properly sealed. Check with your council and a qualified tradesperson.
Who Does Firestopping Work?
Firestopping sits at the intersection of several trades, which is part of why it can be overlooked. In practice:
- Fire protection specialists are the primary experts — they understand tested systems, compliance requirements and IQP certification
- Electricians, plumbers and HVAC technicians often create the penetrations; they should either firestop as they go (using an approved system) or leave the work clearly marked for a fire protection specialist to complete
- Licensed Building Practitioners (LBPs) may carry out or supervise firestopping as part of restricted building work — check LBP for licence classes
- For electrical penetrations, the underlying wiring is restricted electrical work and must be done by a registered electrician — see EWRB
- For plumbing and drainage penetrations, the pipework itself is restricted work under the Plumbers, Gasfitters and Drainlayers Board (PGDB)
The key rule: whoever installs the firestopping must use a tested, assessed system and must be competent to do so. In commercial buildings, the work must be verifiable by an IQP. Do not assume the next trade on site will seal a penetration — confirm responsibility in writing before work starts.
A Note on Safety
Never block, remove or damage existing firestopping — even temporarily — without a plan to reinstate it immediately. Propping open fire doors or leaving penetrations unsealed, even briefly during a renovation, creates real risk. If you discover unsealed penetrations in an existing building, treat it as urgent and engage a fire protection specialist promptly.
When to Call a Professional
Call a qualified fire protection specialist if you are:
- Renovating or fitting out a commercial or multi-unit building and services need to penetrate fire-rated elements
- Unsure whether existing firestopping is compliant or has been disturbed
- Required to provide or renew a BWOF and passive fire protection is listed on your compliance schedule
- Adding new cables, pipes or HVAC runs to an existing building
A good fire protection specialist will specify the correct tested system, install it properly, document the work and — where required — arrange IQP sign-off. You can find qualified local fire protection specialists on tradedirectory.co.nz.
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