CHANGES TO NZBC C PROTECTION FROM FIRE
1 JULY 2014
MBIE have just released amendment 3 to NZBC C/AS1 - C/AS7 and amendment 4 to NZBC C/VM2, effective from 1 July 2014 with a transition period to 1 March 2015. Designers and Specifiers can use old or new documents until 1 March 2015, then only the new ones after that date.
Masterspec will update sections affected by these amendments over the next few months.
The proposed changes for the most part are not radical, but they are wide spread. Some of the highlights are:
C/VM2 and apply to C/AS1 - C/AS7
Refer to the APPENDIX - TABLES FROM C/VM2 at the end of this article to view copies of the following tables.
- New Table B1 Specified Performance for some Flooring Materials. This table provides generic Critical Radiant Flux figures for common generic flooring materials such as; concrete, brick, ceramic or porcelain tiles, wood products, plywood and solid timber. No further testing evidence will be required, unless a higher figure is necessary. (C/VM2 Appendix B)
- Existing Table A1 (generic substrate Group Numbers), a new comment note excludes from table metal or foil faced panels with polymeric (plastics, polystyrene etc) substrates.(C/VM2 Appendix A)
- C/VM2 Table A1 and B1 are now linked to the ASs by new clauses in Appendix C of all ASs, Table A1 by C4.1.2 and Table B1 by C2.1.(VM2 and all ASs)
C/AS1 to AS7
- Definitions - Notional Boundary has been added to cover separate buildings on the same property.
- Table 1.1 Risk Groups and Acceptable Solutions, has additional and changed descriptions under applications. This includes adding: - refuge shelters (AS2), care in the community houses & homes (AS3), temperature controlled storage (AS6). Other changes include:- deletion of limits on outbuildings (AS1), some increased height limits (AS5).
- Notional Boundary for separate buildings on the same property for fire rated external walls. (5.1.2)
- Further fire service vehicle requirements for some multi-unit developments (6.1.1)
C/AS2 to AS7
- Additional requirements for Fire Safety Systems particularly heights related to Type 18 hydrant system in multi storey buildings. (2.2.1)
- Other activities that are permitted in an exitway have had a limit on area introduced by a new clause, which states, "occupy a total floor area of not more than 6m²". This potentially could limit some activities that are traditionally located on/off exitways. Such as; toilets off stair landings and reception counters in exit (entry) lobbies. (3.10.2.d.iii.)
- Additional requirements for smoke lobbies for some lift landings, plus a new Figure 3.17A Lift and Smoke Separation When Landing on a Horizontal Safe Path. In some ASs, lift shaft pressurisation or a type 7 safety system are alternative options to smoke lobbies. (3.10.5)
- New clause on mandatory re-entry from a (25m or higher) safe vertical path (egress stair) back onto floors. AS4 to AS7 require every 4th floor, AS3 requires every floor. (3.15.2.d)
- Smoke detection option deleted from restricted roof/ceiling spaces. (4.15.6)
- Fire dampers are now to comply with AS/NZS 1668.1, and in some ASs also smoke dampers. (4.16.12.a)
- Wood and wood product floors in multi-storey buildings – “thickness of no less than nominally 20mm”. The comments include 19mm particle board and 17mm plywood as acceptable. (4.17.5). (This appears as a rather precise way of defining a minimum, leaving the question of how much less than 20mm is acceptable)
- Clause 4.18.1 covers a smoke alarm turning off AC and ventilation systems, however there is a new Comment added that clarifies this does not apply to non-distributed ventilation & air conditioning (heat pumps etc).
- Projection bays in external walls that must be fire rated, will require fire rated floors. (5.6.8)
- Table 4.1 – Group number requirement for acoustic insulation and pipe insulation within air handling plenums has been deleted in some ASs. (deleted from C/AS 4 and C/AS5) (still required in C/AS2 & C/AS3).
C/AS2, AS4, and AS5 (AS7)
- New Table 2.0 added - Alarm types for various accommodation types and escape heights.
- Higher FRR for doors to plant rooms added. (4.16.1.a & b)
- Plant, boiler and incinerator rooms, FRR reduced from 90 to 45 minutes. (4.10.3)
- Early childhood centres (only) are allowed delayed evacuation (1.1.3).
- Table 4.1 - "Crowd Spaces" has been added, this allows a lower Group Number than previously possible.
- In car park firecells other spaces are now allowed (ticket offices, gate booths, stores) but must be no more than 10m². (4.1.1d)
The range of changes is too extensive to fully list here, refer to amendment 4 for details.
FOAMED PLASTIC OR COMBUSTIBLE INSULATION MATERIALS, AND GROUP NUMBERS
- Definitions - Smoke Separation added.
- New Figure 1.1. The Design Process Overview for C/VM2. Other figure 1.1’s, b to k, are transferred to the commentary.
- More detail added to Fire Modelling Rules for Life Safety Design. (2.2.1)
- More detail on Peak HRR/HRR/m² added to Table 2.1 Pre-flashover Design Fire Characteristics.
- New added clause 2.5 Equivalent Time of Exposure.
- Floors removed from Table 2.4 Conversion Factor Kb for Various Lining Materials.
- Table 3.1 Occupant Densities, amended, activities added and some densities amended.
- 4.1 (BE) – more than 2 escape routes option added for more than 250 occupants.
- 4.2 (UT) – alarm type for more than 150 occupants added.
- 4.5 (HS) – Substantial changes and reorganisation, plus addition of spread of fire from roofs and storage over 3m requirements.
- 4.6 (VS) - Substantial changes under Scenario Description and Method, Note change to 4.6 title, “cladding” has been deleted, also a new part C has been added to cover exposure to lower roofs.
- 4.8 (FO) - References to floors, walkways and racking that are open sided or made of perforated material, have been deleted. (Catwalks are still referred to)
- New Table A2 and clause A1.6 - Covers the selection of common substrates for testing of coatings and other materials to attain a Group Number. (Appendix A)
This is a complex subject, amendments have clarified some aspects but may have confused others.
C/AS1 to C/AS7
Clauses C/AS1 - 4.2, 4.3, CAS2 - AS6 (AS7) - 4.17.2
- The word "exposed" has been deleted from the beginning of "combustible insulation materials".
- "Roof system" has been deleted from the clause(s), so they now only refer to wall and ceiling systems and their Group Number requirements.
This clears up the problem of insulated roof structures that did not form part of the ceiling, they now do not have to have a group number. For instance, a membrane roof system with a membrane directly over polystyrene over concrete (or Ply), and not forming a ceiling. Until now they had to be tested (rarely done) and have a group number associated with the ceiling or a generic insulation group number (also rare). So separate roof system is now ignored when determining the group number for the ceiling system.
Of course composite roof/ceiling systems (like insulated metal panels etc) will still be considered as one system and will be included in the group number requirement.
Clauses C/VM1 - Appendix A - A1.7
- This is a new clause titled "Wall and ceiling elements that include foamed plastics or combustible insulating materials".
This clause seems to indicate, although not clearly, that with foamed plastics and combustible insulation forming part of an element that is covered by certain common surface materials (linings). Then possibly, the element will under certain conditions, have the group number of the surface material and that is all that may be necessary.
Other testing requirements are stated.
Note Metal and foil (faced panels) are not included in the list of acceptable surface materials.
It is reasonably clear that foamed plastics or combustible insulating materials forming part of a roof system ( & not a ceiling system) are now exempt from the group number requirement.
However, for wall and ceiling elements consisting of foamed plastics or combustible insulating materials completely covered by certain acceptable surface materials (linings like plasterboard etc), it is not so clear that the foamed plastics or combustible insulating materials do not influence the group number, and that the group number will only relate to the surface material (lining). Hopefully, there is some further explanation in the new amendments to the Commentary's when they are published.
BCH/AS1 BACKCOUNTRY HUTS
- New clause 2.0.9, that replaces clause D2.3.3.i), of the Hut Procurement Manual. This relates to interior linings and finishes.
The Commentaries to the Acceptable Solutions and Verification Methods have not been amended yet. Indications are that MBIE are working on amendments to the Commentaries and that these will be published at a later date.
If you wish to find out more go to:
MBIE summary of key changes to Acceptable Solutions
MBIE summary of key changes to Verification Method
View the changes to Acceptable Solutions and Verification Method
For general interest, MBIE Building Controls Update No. 162 - Frequently asked questions update
APPENDIX - TABLES FROM C/VM2
Table A1 from C/VM2 Appendix A.
This table provides Group Numbers for generic, substrates or substrates plus coatings. No further testing is required unless a higher group number is required.
Table B1 from C/VM2 Appendix B.
This table provides Critical Radiant Flux (CRF) for some generic flooring material. No further testing is required unless a higher CRF is required.