Fire rating requirements of external balconies

What is the opinion of members on fire rating of (small) external balconies?

The example is a commercial building with a small (say 1 - 1.2m deep) balcony off a mezzanine floor, although it could be a separate firecell. There is no sleeping accommodation and it is all under one title and the deck isn’t needed to be fire rated as an apron and is not an external safe path such as a bridge to outside stairs or a similar case that needs fire rating as of right. The wall underneath may or may not be fire rated and may or may not have something combustible under the balcony such as carpark or garden or may be empty paving.

The client wants to use open mesh or timber decking, as this doesn’t need downpipes or waterproofing decking

It is my own opinion is that it is the same as a floor which should be fire rated as someone may be standing on it, including the fire service, or it may be used for external rescue, but I would be interested in other’s opinions and what is accepted or common practice. Am I overthinking this?

This would not apply to an SH townhouse or domestic house – if only because the floor it is attached to doesn’t need to be fire rated.

Auckland Council get quite confused on this one. is 5.6.9 applicable?

I think Geoff is talking about a C/AS2 4.13 issue.

Hi Geoff. When we had this issue we came to the same conclusion as you. The best counterargument to fire rating we could think of is that if it is open underneath, FENZ would be able to see if the underside was being attacked and therefore know not to stand on it. That said, if they were approaching from inside, perhaps not. If someone inside the firecell were forced onto the balcony to await rescue, you would want them protected. Seems like a good reason to interpret C/AS2 4.13 conservatively.

I’ve always struggled with this issue too. Do you consider the balcony to be a ‘floor’ (no definition given in C/AS2) and so 4.5.2 or 4.13.1 applies? But then a balcony can’t be a fire separation between firecells. We have always taken a similar approach as Jordan, if there is a risk of a fire exposing an occupant or FENZ from beneath, then best to fire rate. If there is no risk at all, then why do you need to? for example a landing in a safe path stair (theoretically a fire sterile space), or a balcony adjacent to a completely fire rated wall. We also consider the likelihood of arson, so ensure the area beneath is secure (only accessible by the occupants).

Hi Rob
That then raises the issue - does your fire engineering analysis become an alternative solution with a minor variation to C/AS2 justifying the relaxation of fire rating requirement for the balcony floor.

Good point Robert, …maybe? I’m still trying to figure out if C/AS2 explicitly says the balcony does or doesn’t need a fire rating! 3.1.1 comes close and only 3.11.4 c)i) specifically requires a FR to the underside. In Geoff’s case you then have to decide whether this small balcony is part of an escape route.

i believe the answer, as it often does lies in the definitions. have a look at the definition of a fire separation and escape route. escape routes commence in a firecell, ie an occupied space within a building, and as noted above a balcony floor that is not on an escape route cannot be defined as a fire separation. the application of 3.11 is qualified in 3.11.1, if an escape route enters a space exposed… ie it must succeed the DEOP/TOP, not precede it. balconies that are not on an escape route are not considered in C/AS2 other than for 5.6.9 or if needed 5.7.12

I’m not sure that all would agree that escape from balconies need not be addressed in fire egress assessments. I think if your balcony was not accessible or was considered as a maintenance platform you might have a case.

Don’t get me wrong I’m not saying that it shouldn’t be addressed just that its falls outside the assumptions of C/AS2. its a bit like someone looking for weathertightness detailing for a round window in E/AS2, you’ll be looking for ever but that doesn’t mean that you should ignore it.

An interesting discussion. To throw some more fuel to the fire :slight_smile:
There is no question that the balcony is part of an escape route:

Escape route A continuous unobstructed route from any occupied space in a building to a final exit to enable occupants to reach a safe place, and shall comprise one or more of the following: open paths and safe paths. Note that doors in an escape route are not considered to be obstructions provided they comply with this Acceptable Solution and D1/AS1.

and it is an occupied space

Occupied space Any space within a building in which a person will be present from time*
*to time during the intended use of the building.

While these definitions also apply to iintermitently occupied service platforms and catwalks, C/AS2 explicitly excludes these as a matter of sensible practicality. The risk is related to exposure time, and the exposure time is miniscule for these spaces which may be used once a month for a few minutes to service plant, put the magic smoke back into an electrical switchboard or have a snooze away from the watching eyes of the boss… To do otherwise would also mean we have to fire rate roofs where these provide access to service plant on the roof. This definition or situation would not apply to a balcony used daily.

In determinations and various court cases, the common practice if a term is not defined is to start with the “common and accepted usage”. In this case, the Collins dictionary says, " The floor of a room is the part of it that you walk on". You walk on a balcony ; therefore, it acts as a floor.

Putting aside the lawyering, and taking an engineering approach, you would need to consider if the fire could threaten the balcony and someone on it. I could imagine, as perhaps an alternative design, a case where the balcony could be justified as not rated. Say the wall below is fire rated to protect from fire spread from inside the building, and it is over a 500’ cliff over the sea so there is no chance of a fire load underneath it, even in the future.
In most cases this would not apply.

Accept that the balcony is an occupied space and therefore an escape route, but (completely playing the devils advocate and throwing accelerant on the fire!) - how then does the balcony ‘floor’ comply with 4.13.1 (i.e. be a fire separation)? 3.1.1 also states escape routes must be protected from a fire within a building, not outside…? Either way I look at this you end up with an alternative solution with a minor variation from C/AS2.


In the particular example Geoff has given, in my view and experience the deck can be unrated for C/AS2 compliance.

Thanks Mike. I would be interested if you and others could expand on your opinion regarding the deck fire rating (or not).

In the example I started off with, the risk to occupants and fire fighters is probably “pretty low”, however I am also interested in the broader case, what are the items that might change someone’s mind to the other view or what people consider to be the key issues.

That aside, the Acceptable Solutions should deal with the reasonable worst case and so we accept it may over cook the requirements in some cases to provide adequate protection in others. We should then interpret it conservatively.

What about property protection requirements for apartments. If the property title includes the Balcony should it not be protected. Once can store anything in the balconies and in many cases they can be partially enclosed depending of the construction.

External Balconies

Rating solutions.

Provide the same rating as the building floor/roof requires at that elevation.

This rating can be achieved with heavy timber and with the use of metal grates, the timbers can be projected out from the building at 12-16" o.c such that anyone timber failure is not an issue for the system.

Is the concern fire from within the building

Is the concern fire from outside the building

Is the concern human imagination.

Inside the building, it’s not required for exiting, it’s a portion of the building facade that is horizontal and has occupancy, but it’s not part of the core building.
If it burns it will need to be put out, but the building isn’t comprised as it’s not a critical element of the building, unless you have a flake for a client with some of the interior structural designs.
Like most things it depends.

hope this helped.

Yes, if each deck is a separate title, horizontally or vertically, it will need to be protected as the requirement is to protect for fire spread across title boundaries, irrespective of any other requirements. It is often overlooked.

What is the consensus for the same scenario if it were a C/AS1 building with one unit over another? C/AS1 has no requirement for spandrels or aprons, and if the units are under the same ownership then property protection doesn’t apply. If the top unit has a balcony, would it need to be protected from the underside?

I can see two approaches. One approach is that the risk to life safety from leaving the balcony unrated is minor. A person on the balcony is likely to notice the effects of fire below, well before they are put in significant danger. The risk is analagous to omitting an apron (permitted by C/AS1).

The other approach would be to consider that this is a feature that is outside the scope of C/AS1 and therefore a different compliance path (e.g. C/AS2) must be used, in which case the deck would essentially need to be a fire rated apron.

What is your opinion, and would your answer change depending on whether the lower unit also had a deck directly underneath the upper balcony?

My view is that for the purposes of complying with the acceptable solutions the deck is a floor. So if the floor is required to be a fire separation then the deck is also required to be a fire separation. I suspect that the rationale behind that is that the occupants in a separate firecell above and out on a deck may not be aware of a fire in the firecell below. Flashover in the firecell below could catch occupants out on a non fire rated deck.
In the absence of any clear directive from the acceptable solutions I would treat the deck the same as a floor. ie in a single household unit upper floors (and decks) are not required to be fire separations while with separate household units one above the other the inter unit floor (and consequently the deck) is required to be a fire separation.

Thanks Robert, in hindsight I’m not sure why I saw it any other way!