C/AS1 and Sprinklers

(Robert Peart) #1

This query will need to ultimately go to MBIE but I thought it would be a good idea to canvas the opinions of the SFPE Forum.
C/AS1 make many references to “sprinklers”:
NZS 4515:2009 Fire sprinkler systems for life safety in sleeping occupancies (up to 2000 m²)
NZS 4517:2010 Fire Sprinkler Systems for Houses
NZS4541:2013 Automatic fire sprinkler systems.

My question is about the intent and the legal interpretation of C/AS1 5.1.1

5.1.1 Where the building is protected with a sprinkler system, external walls do not need a FRR.

Is a NZS 4517 sprinkler system a “sprinkler system” for the purpose of C/AS1 5.1.1?

Here is a code lawyers argument that suggests a NZS 4517 sprinkler system is a “sprinkler system” for the purposes of C/AS1 5.1.1.
There are 8 references to a sprinkler system in the C/AS1 text if you ignore the references section and comments:

  1. Table 2.1 - Type 6 and Type 7 Automatic fire sprinkler systems. Note that there is no use of the term “Type 6” or “Type 7” anywhere else in C/AS1.
  2. Table 3.2 refers to NZS 4515 and NZS 4517 sprinkler systems in the context of escape route travel distances.
  3. 5.1.1 refers to a sprinkler system of an undetermined standard in the context of fire rated external walls.
  4. 5.3.2 refers to a NZS 4515 sprinkler system in the context of fire rated lower roofs.
  5. Table 5.1 refers to NZS 4515 sprinkler systems in the context of external wall claddings.
  6. 6.1.1 refers to a NZS 4515 sprinkler system in the context of FENZ vehicle access.
  7. A1.1.1 requires sprinkler systems, except where specified, to comply with Appendix B.
  8. Appendix B places constraints on NZS 4541 and NZS 4515 sprinkler systems. Note that NZS 4541 sprinkler systems are not even mentioned in the text of C/AS1 so I’m not sure why it is included in Appendix B.

All references in the text specify the pertinent standard except for 5.1.1 which suggests that either NZS 4515 or NZS 4517 can be applied for the relief from fire rating external walls. Is this deliberate or unintended?
It could be a deliberate incentive for sprinkler protection of houses.

I reiterate that there are no references that requires type 6 or type 7 fire safety systems (so why are they in table 2.1?)

I would be grateful for some feedback before I fire this off to MBIE.

Regards
Robert Peart

(Nick Saunders) #2

Hi Robert

I think you should consider the following:

Where a particular standard is not mentioned and a “sprinkler system” is specified it should be interpreted as a sprinkler system that is installed as per its scope of use, i.e. 4517 for single houses and 4515 for multi-residential buildings up to its’ limits.

I would suggest that Type 6 and Type 7 are cited in Tables 2.1 and 3.2 because there is an allowance to extend travel distances if the designer chooses to install a Type 6 or Type 7 system.

Appendix B is standard across all of the Acceptable Solutions hence the reference to NZS 4541.

Just my thoughts

Regards

Nick

(Robert Peart) #3

Thanks Nick

C/AS1 allows for fire separated minor units within a “house” say. C/AS1 also provides for other arrangements where either multiple NZS 4517 systems or a single NZS 4515 system could be installed depending on the desired outcome.
NZS 4517 also allows for an attached self contained unit (NZS 4517 1.1.2).
I have taken this as allowing for the use of a NZS 4517 sprinkler system throughout the building containing a major household unit and an attached minor household unit - eg granny flat.
For some reason the writers of C/AS1 have refrained from using the terms “type 6” and “type 7” in table 3.2 and elsewhere even though what is specified is clearly a type 6 and type 7 system. All the other acceptable solutions use the “type 6” and “type 7” terminology. This appears to be very deliberate.
There is also an allowance to extend travel distances with a NZS 4517 sprinkler system. Note that a NZS 4517 sprinkler system does not fit in the F7/AS1 definition of a type 6 fire safety system.

Regards
Robert

(Michael James) #4

Hi Robert,

I put this questions to MBIE a couple of years ago and the response was that in NZS4517 the stated purpose is life safety and not property protection therefore it could not be used for the boundary wall scenario. However C/AS1 is very ambiguous on this.

Regards,

Michael

(Robert Peart) #5

Thanks Michael

That argument shouldn’t hold water. Reading the forward of NZS 4515:

NZS 4515 is a sprinkler Standard that has been developed where the primary purpose is to provide life safety to buildings primarily used for sleeping occupancies… The foward goes on to say that the original NZS 4515 was split into 2 standards - the current NZS 4515 (smaller commercial sleeping occupancies) and NZS 4517 (private houses).

It begs the question: is a house with an attached granny flat closer to a house or a small commercial sleeping occupancy?

NZS 4515 certainly would provide more property protection than a NZS 4517 system.
As you say C/AS1 is very ambiguous. Sounds like we need some case law (determinations).

Regards
Robert

(Chris Mak) #6

NZS4517 was based on the research carried out by BRANZ. Without looking it up, the stated objective was to reduce the loss of life by fire in a building using the design basis from that research by 70%. Property protection will be a side benefit of a NZS4517 and not a design objective.

Robert - your quote a Code Lawyer. I have heard Prof Arnold Dix state “complying with standards will not protect you from claims of negligence.”

(Robert Peart) #7

Thanks Chris

You should only play code lawyers if the engineering backs up the approach. Sometime the standards and/or acceptable solutions create problems for arrangements that can be substantiated from first principles. As you know that’s just because standards etc cannot cope with all situations. In those cases I see no problem with taking a "code lawyer " approach providing your fundamentals withstand scrutiny.

We all know that two houses 2 m apart will not prevent fire spread between the houses. However there is a significant community benefit from allowing this arrangement and historically there does not appear to be a major problem with this arrangement. So BIA/Ministry of Housing/MBIE over the years have built various compromises into the acceptable solutions. It is just sometimes not very clear what they are and what their intentions are.