Housing is rapidly changing in New Zealand with shortage of land available in cities and the need to live near transport links with close proximity to a CBD. Medium density housing is now the new norm.
The New Zealand fire code for housing is Acceptable Solution C/AS1 which has not kept pace with new housing design methods. Gone are the days of a single house on a quarter acre section instead we are now designing several houses on one site with only narrow access pathways.
Medium density allows several houses located at the back of a section where escape from an adjacent house fire would be impossible. This also hampers the ability of FENZ (Fire and Emergency New Zealand) to fight fire or assist with rescue.
In 2019 MBIE Determination 2019/062 FENZ raised concerns with multi-unit dwellings on one site with narrow unprotected routes between dwellings and less open space between dwellings.
C/AS1 was developed with the 1m separation to boundaries based on the assumption that FENZ can apply water from the street to prevent fire spread. Without this access it is impossible for FENZ ability to apply water so is the 1m rule still suitable?
Of greater concern is the fire rating of 30 minutes FRR. With the inability to escape for the back units and limitation of FENZ to fight fire the only protection is a 30 minute FRR fire wall to the neighbor. Is this sufficient for modern furnishings and large scale housing designs? C/AS1 does not address the more complicated issue of passive fire protection for penetrations in these walls.
The only fire safety feature in multi-unit dwellings is battery powered smoke alarms. These can easily be removed so are these adequate to protect our families and communities?
There is no requirement for fire rated junctions to roofs, eaves, overhangs or balconies. With housing of higher density can fire jump across fire separations?
The housing fire code is based on defend-in-place evacuation strategy i.e. if the adjacent house is on fire you are supposed to stay where you are. UK has the same strategy for high riser domestic dwellings which is now deemed inadequate. It is a human right to be able to leave a building if anyone wishes to do so.
I am genuinely concerned for modern housing designs which is deemed to comply Acceptable Solution C/AS1. This code is out of date and urgently needs an overhaul to allow for the more common multi-unit developments.
My recommendation for multi-units dwellings is:
- Minimum 60 minutes FRR fire ratings between dwellings and to other property.
- Mains powered interconnected smoke alarms throughout the house.
- Provide at least 2m escape route from all houses for occupants and Fire Service
- Extend fire rating through eaves and overhangs where possible and address subfloor fire separation.
MBIE have drafted an amendment to C/AS1 which addresses the above. However, delays in issue of this draft mean we continue to have inadequate code for design of multi-unit dwellings in New Zealand.