Fire Engineering FAQs
See below for a list of frequently asked quesitons.
If you have one not covered below feel free to contact us.
Do we need sprinklers in a warehouse?
In general terms, a sprinkler system is not likely to be required for warehouses with the following characteristics:
- Not containing highly combustible materials such as fuels and plastics
- Stud heights less than 8m
- An area less than 4200sqm
- Small intermediate floors
Where a warehouse exceeds these criteria, the options are either to provide sprinklers, or to perform a gap analysis or computer modelling analysis. THE DESIGNFIRE team can assist with either of these.
Do we need sprinklers in a Boarding House?
Generally speaking, a boarding house in a low-rise building with more than one exit may well not require a sprinkler system.
Do we require firewalls when subdividing existing large shops into multiple units or tenancies?
Firewalls between individual shops are not always required – this depends somewhat on the use of unit titles.
Where separate Unit Titles are proposed – if the shops are divided into separate titles – then firewalls are required. The actual fire rating performance requirement will depend on the use of the space, subject to a fire design assessment. The firewalls in this case are triggered by the requirement under the Building Act – Protection of Neighbouring Properties.
Where Unit Titles are not proposed – for example, where simple divisions are proposed for creating two or more shops under one title – firewalls are often not required as long as the proposed use of the units or egress provisions do not change.
There are, however, some cases where fire walls are required, without unit titling. The reasons could be due to Increased Occupancy, Change of Use, Open Path Separation Requirement, or other special reasons.
A fire consultant must be engaged to confirm this – please get in touch with THE DESIGNFIRE team for help in this area.
Does a “right of way” among residential housing require a fire rating? Is it a 'road'?
The question here is whether the right of way is classified as a road or a public open space. It comes down to the definition of ‘relevant boundary’.
“relevant boundary means the boundary of an allotment that is other property in relation to the building in question and from which is measured the separation between the building and that other property; and for the external wall of any building, the relevant boundary is the nearest of—
“(a)a boundary of a freehold allotment, except that if the other property is a road, railway line, or public open space, the relevant boundary is the boundary on the far side of that other property; or…
This usually means, then, that no fire rating would be required in such cases.
The common confusion is on the meaning of ‘Road’.
There is no definition of the term ‘Road’ in the Building Act. And according to the NZTA, there is wide scope in the definition of ‘Road’:
“The common law that we inherited from England used a very simple test to determine what is a road: Essentially, there had to be a ‘right of way’ or ‘right of passage’ granted to the public by the landowner. It didn’t matter whether the land was publicly or privately owned – it was the permission for public use that counted.”
The statutory definition (which for the enforcement purpose of NZTA, has a wider definition than the traditional meaning of ‘Road’) covers places to which the public have access. In this, ‘public’ means the public in general and not just a section of the public; and it is not enough that the place is physically open to the public – they must be shown to be actually using it.
Whether we’re applying the common law definition of ‘road’ or the NZTA definition, the confusion surrounds a small private ‘Right of way’ – which may have a security gate and may only be used by a specific group of people who own lots served by it.
In this case, the fire rating requirement can usually apply to the inside boundary line. For bigger subdivisions or development projects, where the driveway is vested to the council where anyone including general public is free to use it, then ‘far’ side of the boundary can be taken to determine the fire rating.
This is another one of those council issues that is best dealt with by a firm with experience in council legislation and fire ratings. Please get in touch with us for more information.
What are the fire compliance implications of a boarding house conversion?
If you’re considering opening your house up to boarders – for example, taking in overseas students – there are things you need to consider which determine whether the conversion involves any building or fire compliance requirements.
First and foremost, the Building Act stipulates different Purpose Groups and Risk Groups based on the number of people in the house and how they live together (i.e. as one family-type environment or as independent renters in separate rooms). How the building is occupied then helps determine whether the building is considered a household unit or not, which in turn, determines what type of Fire Compliance Document may be needed.
In short, this is not a simple scenario to assess as the Purpose Groups and Risk Groups of the Building Act are quite complex. For an example we’ve worked on, you can read the full story here in our blog.
If you have a specific conversion in mind, please get in touch with us for more clarification.
Do we require a fire rating for a residential house where walls are less than 1 metre to from the boundary?
Generally speaking, where the residential house walls are MORE than 1 metre from the boundary, the wall does not require a fire rating to protect neighbouring buildings. A clearance of 1 metre or more is deemed to meet the provisions under the Building Act.
Where that distance is measured from is important to note.
Be aware that in some residential developments, the foundations of the building are in the plans as ‘1 metre’ to the boundary. However, the 1 metre clearance is required from the ‘cladding’ of the wall to the boundary. In many cases, the cladding will be over the ‘foundations’ line and can sometimes count for an extra 40 to 50mm (reducing the 1 metre clearance by that amount). There are also tolerance issues to the measured surveying data and the build conditions.
Where the wall cladding is less than 1 metre to the boundary, the walls are required to be firewalls. The upgrade to firewalls is not just about fire rating performance, but also about associated surface finish requirements and structural stability requirements as well.
All of these elements can have significant financial implications on the build. It’s advisable to have an experienced fire consultant review your plans if you are in doubt about whether your walls are far enough from the boundary.
What are the regulations around fire ratings for building easement areas?
An easement is the right to use or cross someone else’s property for a limited purpose – usually a right of way, or a shared boundary wall. Whether or not an easement needs a fire resistance rating (FRR) depends on many things, including the proximity of buildings and the purpose of the easement.
THE DESIGNFIRE team experienced just how complicated the interpretation of the building code could be in this area when we worked on a terraced housing development project. The ‘common easement area’ directly abutted the building and it was designated for a proposed soakage system.
We needed clarity over whether the easement was considered a building or an open space. whether the soak pit would be considered a council storm water related system, and a few other rather complex details of the project. You can read the full story here in our blog.
In short, fire ratings and building easement areas are not a clear-cut area of the building code. THE DESIGNFIRE team are extremely experienced in this area and can help save you significant time interpreting the relevant regulations affecting your project.
Three-storey House with a Minor Dwelling - Fire Engineering Implication
For a three-storey house with a minor dwelling, the Acceptable Solutions under Building Act is not the only method to comply with the Building Code, but it is the most commonly used method to demonstrate compliance with the performance requirement of the Building Code. Without further justification or technical data, the Acceptable Solution is ‘deemed’ to comply.
For fire compliance, there are two documents available to adopt in Acceptable Solutions.
C/AS1 is commonly used for standalone housing, low-rise terraced housing development, boarding houses with limits, and outbuildings.
C/AS2 is commonly used for other types of building (except a few specialized buildings) not covered under C/AS1. It also includes more complex accommodation buildings such as apartments, and transient accommodation including hotels, motels, and educational accommodation.
It is also noted that other methods of compliance include the Verification method and Alternative solutions.
In the realm of low-level residential development, such as standalone housing or terraced house development, C/AS1 has been typically used to prove compliance.
The latest amendment of C/AS1 (amendment 5, at the time of writing) now includes additional scope clarification in relation to vertically stacked household units on top of the other, to be still included in C/AS1, but only when each household unit has a single-storey.
For example, C/AS1 does not include three-storey houses with a minor dwelling at the lowest level. This poses some challenges to designers and fire consultants to be able to present such buildings with suitable justification to demonstrate compliance.
One of the other options is to demonstrate compliance with C/AS2, but this raises other practical compliance problems. Compliance with C/AS2 usually brings in additional fire safety features, requirements that are not commonly found in such types of buildings – including commercial automatic fire alarm systems, emergency lighting, and so forth.
It is also noted that these systems would require scheduled maintenance to keep them effective under the building warrant of fitness regime. However, such a building does not require a building warrant of fitness, so it is most likely such systems will not be maintained, compromising the life safety provision as time goes on.
As far as we understand, at the time of writing, for such type of building, there has been no consensus compliance approach that has been universally accepted by the council. At some stage, someone may need to apply for a formal determination process to have clearer guidance to show compliance when submitting building consent applications.
For now, we have consulted with a few other consultants and councils to formulate our design strategy to tackle such issues to balance life safety risk with practicality. At this stage, we think an alternative solution approach may be required for such types of buildings that are backed up by robust justification. Some of our engineering approaches have been accepted by the council, but I am open to further discussions and other comments around this matter.
What are the key rules around the external egress provision for terraced housing development, and how does the C/AS1 Fire Acceptable Solution document influence this?
Auckland councils standardly advise a 2m radiation clearance for separation requirements, a guidance designed primarily to ensure occupant safety and to curtail fire spread. However, some industry experts argue that a reduced clearance may be sufficiently safe for simpler residential structures, given their lesser need for extensive external fire spread prevention. This viewpoint considers the current stipulations found within the compliance documents.
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