Meeting Fire Performance for Existing Wooden Struc

Recently, there have been instances where existing timber structures have had to be removed because of uncertainty around fire performance. Many other projects have significant costs attributed to keeping existing timber structures and meeting council and code standards. Tech Coatings provides a multitude of AS/NZS tested solutions for timber that allow cost-effective treatment of existing timber, whether exposed, concealed or in penetrations.

When looking at the fire resistance rating required by different timber elements within an existing structure, it is important to understand what each element is required to do.

Structural support

Historically, buildings in New Zealand used native hardwood timber extensively as structural members, such as beams and columns. These members are designed to work the same as structural steel does today, and as such the FRR is determined by the structural engineer. This often means that the FRR of the existing timber members is inadequate.

FBL-100 offers structural members valuable minutes of extra protection when exposed to the heat of fire over 200°C. At 200°C, timber starts to go through a process of thermal breakdown into combustible gases, causing charring. It’s at this time, that FBL-100 forms a carbonous char that insulates and protects the timber not only from transfer of heat, but also from direct attack of flames.

Horizontal fire barrier

Native hardwood has also been used extensively as part of mid-floor systems, such as joists and flooring, which are a horizontal fire barrier. As such, the FRR is determined by the requirements of NZBC Clause C.

The application of FBL-100 to the underside of the floor/ceiling helps by adding to the self-protecting nature of timber, insulating the exposed timber, slowing charring, and increasing the likelihood of the timber structure surviving fire.

FBL-100’s ability to help protect timber means that it is now possible to keep these natural timber elements in existing building stock.

FBL-100 is the only coating that has been tested in Australasia on locally sourced materials as per the current New Zealand building code, using AS 1530.4:2014 and AS/ISO 5660.

FBL-100, Multiple Substrate Intumescent Coating System

Tech Coatings

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FBL-100 is an Intumescent Coating System especially designed for interior passive fire protection of multiple substrates that will be exposed to view.

FBL-100 has been tested as per NZBC C/AS2 -C/AS6 Appendix C, for interior use only, as part of a providing a 'Fire Resistance Rating' (FRR) of 60/60/60 on either

Timber (or better) framed walls exposed to fire from either or both sides (two-way FRR), or exposed to fire from the coated side (one way FRR) and
Timber framed (or better) floor/ceiling systems exposed to fire from below in residential, commercial or industrial buildings on the following substrates:

13mm GIB Standard Plasterboard,
6mm fibre cement sheet,
12mm plywood
Exposed timber floors/ceilings (underside only)

FBL-100 has been tested as per NZBC C/VM2 Appendix A and can be used to prevent spread of fire on interior wall or ceiling substrates. It achieves Group 2-S on Type 1 (most reactive) as per C/VM2 A1.6, Table A2
FBL-100 can be applied over existing pre-painted surfaces
FBL-100 Can be applied on new or existing substrates, subject to fixing pattern (refer to: Appendix A, Table 1, Substrate Fixing).
FBL-100 can be applied to structural timber works and can also be used to protect internal load bearing wood from fire, therefore reducing cross-sectional area requirements, or omitting the use of encapsulating boards.
For the purpose of defining the 'Level of finish' for pre-application of FBL-100 —
The surface that is to be coated must be finished to Level 4, minimum (AS/NZS 2589)
For the purpose of defining the 'Level of Finish' for post-application of FBL-100 —
Once FBL-100 has been applied, it achieves an indicative Level 4 for walls and ceilings, although the finish level will be as per the sample provided by the 'TCNZ Certified Applicator'
FBL-100 has been tested to be used on building materials and building practices used in projects designed and built on and after 1995
For the purpose of defining the Classification of 'Interior Environments' that FBL-100 may be used in, is as per AS/NZS 2311.1 — Section 2, Table 2.1:

FBL-100 may be used in Category C1 (Very Low) and C2 (Low) environments

Timber (or better) framed walls exposed to fire from either or both sides (two-way FRR), or exposed to fire from the coated side (one way FRR) and
Timber framed (or better) floor/ceiling systems exposed to fire from below in residential, commercial or industrial buildings on the following substrates:

13mm GIB Standard Plasterboard,
6mm fibre cement sheet,
12mm plywood
Exposed timber floors/ceilings (underside only)

13mm GIB Standard Plasterboard,
6mm fibre cement sheet,
12mm plywood
Exposed timber floors/ceilings (underside only)

FBL-100 may be used in Category C1 (Very Low) and C2 (Low) environments

B2.3.1 Performance — Building elements must, with only normal maintenance, continue to satisfy the performance requirements of this code for the lesser of the specified intended life of the building, if stated, or (c) 5 years if:
- (i) The building elements (including services, linings, renewable protective coatings, and fixtures) are easy to access and replace, and
- (ii) Failure of those building elements to comply with the building code would be easily detected during normal use of the building

(i) The building elements (including services, linings, renewable protective coatings, and fixtures) are easy to access and replace, and
(ii) Failure of those building elements to comply with the building code would be easily detected during normal use of the building

FBL-100 has been tested and assessed to:

AS 1530.4:2014 – Methods for fire tests on building materials, components and structures: Fire resistance tests for elements of construction; and
ISO 9705:1993 — Fire Tests: Full-scale room test for surface products

As per the following:
- Appendix C (normative) Test Methods of any of the NZBC – C/Acceptable Solutions (C/AS2 — C/AS6)
- Appendix A (normative): Establishing Group Numbers for lining materials of NZBC – C/Verification Method Two (C/VM2)
Therefore, is able to be used where the New Zealand Building code calls for a Fire Resistance Rating (FRR) or where a Group 2-S or better Interior Lining is needed

AS 1530.4:2014 – Methods for fire tests on building materials, components and structures: Fire resistance tests for elements of construction; and
ISO 9705:1993 — Fire Tests: Full-scale room test for surface products

Appendix C (normative) Test Methods of any of the NZBC – C/Acceptable Solutions (C/AS2 — C/AS6)
Appendix A (normative): Establishing Group Numbers for lining materials of NZBC – C/Verification Method Two (C/VM2)

FBL-100 has been designed to achieve a NZBC Group Number for surface finishes as per Appendix A of NZBC C/VM2.FBL-100 has been tested and assessed to achieve a Group 2-S on Type 1 substrates or better as per Appendix A1.6 Table A2 of NZBC C/VM2

All relevant certificates, assessments and reports are available upon request.

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