Fire Performance: Oak Flooring, Wall and Ceiling Linings
Fire performance decides whether timber can be used in a room at all. In New Zealand it is governed by clause C3 of the Building Code, and floors and wall and ceiling linings are measured in two different ways. This page sets out what we have tested, what each result means, and how to specify Marchand oak so it meets the rating your project requires.
At a glance
| Product | Measure | Result | Evidence |
|---|---|---|---|
| 20mm engineered oak flooring | Critical radiant flux, AS ISO 9239.1 | 5.0 kW/m² | CSIRO, 28 May 2024. Report published |
| 12mm wall and ceiling board, factory lacquer | Group number, NZBC C3 | Group 3 | Manufacturer's technical specification |
| 12mm wall and ceiling board, coated with FireZone 92 | Group number, NZBC C3 | Group 1-S | Confirmed by Zone Architectural Products against the board's construction |
| 14mm Noir Bandsawn wall and ceiling board | Group number, NZBC C3 | Group 3, factory lacquer | Manufacturer's technical specification. Talk to us before specifying a higher group |
Floors: critical radiant flux
A floor is judged by how much radiant heat it takes before flame will spread across its surface. That figure is the critical radiant flux, measured in kilowatts per square metre. The higher the number, the more heat the floor withstands.
Our 20mm engineered oak was tested by CSIRO to AS ISO 9239.1 and returned 5.0 kW/m². The Building Code sets floor covering thresholds of 2.2 kW/m² and, in its more demanding locations, 4.5 kW/m². Our result sits above both.
The floor was tested as supplied, with its factory UV lacquer. No fire coating is needed and nothing is applied on site. The full report is on our Resources page.
Walls and ceilings: Group numbers
Linings are classified from Group 1 to Group 4 using cone calorimeter testing to ISO 5660. Group 1 contributes least to a fire; Group 4 contributes most. The suffix S means the lining also meets the limit on smoke production.
The group a lining must achieve depends on how the building is used, where the lining sits within it (an exitway is treated more strictly than an occupied room), and whether the building is sprinklered. Hospitality, retail, workplace, education, healthcare and multi-unit residential projects commonly require Group 1-S or Group 2-S in some or all spaces. Your fire engineer or designer confirms the requirement.
With its standard factory lacquer, our wall and ceiling board is recorded as Group 3 in our manufacturer's technical specification. Where a project calls for more, the 12mm board achieves Group 1-S, the highest classification, with an intumescent coating.
How the 12mm board achieves Group 1-S
We work with FireZone 92, the intumescent coating system from Zone Architectural Products, New Zealand specialists in passive fire protection for timber. In a fire, the coating swells into an insulating char that slows the timber's contribution to the fire.
Zone reviewed the construction of our 12mm board, a 1.2mm European oak face bonded to a 10.8mm cross-laminated hardwood core at around 655 kg/m³, and confirmed it meets their standard requirements to achieve Group 1-S when coated with FireZone 92, without separate testing.
FireZone 92 is applied over our factory lacquer, and a trial application on our boards was completed in 2025. We hold coated samples, so the finish can be judged beside the uncoated board before it is specified.
Specifying Group 1-S
- Specify it at the outset. The coating is an additional step with its own cost and lead time. Planned from the start, it is straightforward. Retrofitted to a finished ceiling, it is not.
- Use an approved applicator. The rating depends on the coating being applied correctly, at the specified rate, by a FireZone applicator. Zone is one of them. Tell us at order stage that the project needs Group 1-S and we will connect you with an applicator.
- Keep the paperwork. Ask the applicator for documentation confirming the application, for your consent file.
- Confirm the board. The Group 1-S confirmation covers the 12mm wall and ceiling board in all twelve colours. For Noir Bandsawn, talk to us before specifying.
Suggested specification wording
Wall and ceiling linings: Marchand 12mm European oak wall and ceiling board, [colour], 120mm × 2400mm, factory UV lacquer, coated with FireZone 92 intumescent system by an approved FireZone applicator to achieve Group 1-S under NZBC clause C3. Direct fixed, tongue and groove, glued, to the Marchand Wall and Ceiling Installation Guide.
We will review the clause against your project before it goes out. Marchand is a Masterspec Product Partner, and our branded work sections sit inside Masterspec.
One material, floor to ceiling
The wall and ceiling board is exactly half the width of the floor board, so every second join on the wall aligns with a join on the floor. With the floor above both Code thresholds as supplied, and the linings achieving Group 1-S when coated, a commercial interior can be one continuous oak material without a compromise in compliance.
What we can provide
- The CSIRO critical radiant flux report for the flooring
- Zone Architectural Products' confirmation for the 12mm board, on request
- Coated and uncoated samples, side by side
- Specification wording for your project, reviewed before issue
- An introduction to an approved FireZone applicator
Contact us with the project name and the group number required, and we will tell you exactly what we can evidence for the rooms involved.
Frequently asked questions
What fire rating does Marchand oak flooring have?
A critical radiant flux of 5.0 kW/m², tested by CSIRO to AS ISO 9239.1. That is above the 2.2 kW/m² and 4.5 kW/m² thresholds the Building Code sets for floor coverings.
Does the floor need a fire coating?
No. The result was achieved with the standard factory lacquer. Nothing is added on site.
What does Group 1-S mean?
It is the highest classification for wall and ceiling linings under NZBC clause C3. Group 1 is the lowest contribution to fire, and S confirms the lining also meets the smoke production limit.
Can oak wall panelling be used in a commercial fit-out in New Zealand?
Yes, at the group number the space requires. Our 12mm wall and ceiling board achieves Group 1-S when coated with FireZone 92, which covers the most demanding lining requirements.
Does the fire coating change how the oak looks?
FireZone 92 is applied over our factory lacquer. We hold coated samples so you can see the finish for yourself beside the uncoated board before specifying.
Who applies the coating?
An approved FireZone applicator, of which Zone Architectural Products is one. We can connect you with an applicator when the order is placed.
What rating do the wall boards have without the coating?
Group 3, as recorded in our manufacturer's technical specification. Many homes and some commercial spaces accept Group 3. Your fire engineer or designer will confirm.
Does the Group 1-S confirmation cover Noir Bandsawn?
It covers the 12mm board in all twelve of its colours. Noir Bandsawn is a 14mm board with a different finish, so talk to us before specifying it where a higher group is required.
Who decides what group number my project needs?
Your fire engineer or designer, based on the building's use, the location of the lining and whether the building is sprinklered. Give us the requirement and we will confirm how our oak meets it.
Related
- Specification and compliance: full test evidence
- Technical specifications
- Wall and ceiling specification guide
- For architects and designers
- All technical documents
Last reviewed September 2026.