Renovating your home or commercial building often means cutting holes through walls, floors and ceilings — and if those elements are fire-rated, every penetration must be properly sealed to restore the original fire rating. Getting this wrong can put lives at risk and may also create serious compliance issues under the NZ Building Code.
What Is a Fire Rating and Why Does It Matter?
A fire rating (sometimes called a fire-resistance rating or FRR) describes how long a building element — a wall, floor, or ceiling — can withstand fire before it fails structurally, loses integrity, or allows heat to pass through. Ratings are typically expressed in minutes (e.g. 30, 60, 90 or 120 minutes). These ratings are central to NZ Building Code Clause C, which covers protection from fire, and they exist to give occupants time to escape and to limit the spread of fire between compartments.
When you cut a hole through a fire-rated element — to run a pipe, cable, duct or beam — you create a penetration that can act like a chimney, allowing fire, smoke and toxic gases to travel rapidly from one compartment to another. Restoring the original rating requires firestopping.
Common Renovation Scenarios That Affect Fire Ratings
- Running new electrical cables or conduit through fire-rated walls or floors
- Installing plumbing pipes (especially plastic pipes, which melt and leave open holes)
- Adding or relocating HVAC ducts through fire-rated compartment boundaries
- Cutting access holes for structural work or insulation
- Removing and reinstating fire-rated linings such as GIB plasterboard systems
Understanding Firestopping Products
Firestopping is not just filling a gap with standard silicone or expanding foam. You need products that are tested and rated for the specific application. Common firestopping products used in NZ include:
| Product Type | Typical Use |
|---|---|
| Intumescent sealant | Sealing around cables, small pipes and gaps in plasterboard |
| Intumescent pipe collars/wraps | Plastic pipes — the collar expands when heated to close the hole as the pipe melts |
| Firestopping pillows/blocks | Large cable bundles or multi-service penetrations |
| Fire-rated duct wrap or dampers | HVAC ducts passing through fire-rated walls |
| Fire-rated mortar or board | Larger penetrations in concrete or masonry |
Suppliers such as Sika and Ardex offer firestopping product ranges in NZ. Always check that the product you choose has been tested to the relevant NZ Standard for the specific penetration type, substrate and fire-resistance period required. Your fire protection specialist or the product manufacturer can confirm suitability.
The Golden Rules of Firestopping
- Like for like: The firestopping system must achieve at least the same fire-resistance rating as the element being penetrated.
- Follow the tested system: Firestopping products are tested as complete systems — specific product, specific substrate, specific penetration size. Mixing and matching components can void the rating. Always follow the manufacturer's tested installation instructions exactly.
- Document everything: Keep records of what products were used, where, and by whom. This is especially important in commercial buildings where a compliance schedule and Building Warrant of Fitness (BWOF) may apply.
- Don't assume standard products work: Regular silicone, standard expanding foam and ordinary plasterboard filler are not firestopping products.
Do You Need a Building Consent?
This depends on the scope of your renovation. Under the Building Act 2004, work that affects fire-rated elements will generally require a building consent. Schedule 1 of the Building Act lists exemptions for minor work, but firestopping penetrations in fire-rated construction are unlikely to qualify as exempt if they affect the fire-resistance of the building. Always check with your local council before starting work — getting this wrong can cause costly problems when you sell or insure the property. MBIE Building Performance has useful guidance on when consents are required.
Fire-Rated Linings: GIB and Other Systems
Many NZ homes and commercial buildings use GIB plasterboard systems to achieve fire ratings in walls and ceilings. If you need to remove and reinstate GIB lining as part of a renovation, the reinstatement must match the original tested system — the correct board thickness, fixing pattern, stopping and jointing. GIB publishes its own fire-rated system specifications; your installer should follow these precisely.
Commercial Buildings: Specified Systems and IQPs
If your renovation is in a commercial or multi-unit building, fire-rated elements are likely specified systems under the building's compliance schedule. Any work affecting these systems must be carried out and signed off by a suitably qualified person. An Independent Qualified Person (IQP), registered with your local council, is required to inspect and certify that specified systems are performing correctly. The building owner is responsible for maintaining the BWOF annually. Speak to your council and engage a licensed fire protection specialist before touching anything in these buildings.
When to Call a Professional
Firestopping is a specialist skill. You should engage a licensed fire protection specialist or a suitably qualified tradesperson for:
- Any penetration through a fire-rated wall, floor or ceiling in a commercial building
- Plastic pipe penetrations requiring intumescent collars (incorrect installation is a common and dangerous mistake)
- HVAC duct penetrations requiring fire dampers
- Any situation where a building consent is required
- Reinstatement of fire-rated linings after structural work
For residential work, even if you are doing a DIY renovation, it is strongly recommended to have a fire protection specialist assess and seal any penetrations through fire-rated elements. A mistake here is not just a compliance issue — it can cost lives. You can find qualified local fire protection specialists on tradedirectory.co.nz.
For general fire-safety guidance, Fire and Emergency New Zealand (FENZ) is an excellent resource. For rental properties, check your smoke alarm obligations with Tenancy Services.
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