2021 NCC Seminars: This building is sprinklered – I can use 1.2 kw-m2 carpet, can’t I?

This building is sprinkler protected. I can use 1.2 kw/m²carpet, can't I? This is a question about C1.10 for floor coverings, but its relevant to more than just that, and you'll see why in a minute. So, lets say we're checking carpet in a Class 2 sole-occ unit, sprinklered building. 1.2 kilowatt per square metre carpet is okay, isn't it?

Well, C1.10 controls fire hazard properties. And for floor coverings, it sends you to Specification C1.10 Clause 3. And Table 2 in Clause 3 has a series of minimum values for the floor covering's critical radiant flux.

A lower value is less stringent than a higher value. And a lower value is allowed when there is less risk, such as when your building is sprinkler protected, because the sprinklers are going control any fire that does occur. And as you can see, more often than not, 1.2 kilowatts per square metre is an appropriate critical radiant flux for most floor coverings in a sprinkler protected building, such as in a class 2 sole-occupancy unit.

It's not uncommon for a sprinkler protected building to receive concessions because sprinkler protection mitigates against a lot of hazards. Except Table 2 doesn't look exactly like this. I've left something out, because I adjusted the top row. Now, to be fair, it looked like the previous slide for many years, until the FPAA 101D and 101H sprinkler systems were introduced in 2019.

The NCC often permits concessions for sprinkler protected buildings, or has requirements related to a sprinkler system, but to get those concessions or have those requirements apply, the sprinkler systems need to have a very high level of reliability. Now the 101H and 101D systems are new. And evidence hasn't been developed to show that the FPAA systems are suitable.

Therefore they're excluded here in Table 2. For the majority of concessions for sprinkler protected buildings, you'll see text in brackets like you see in the first row here, other than a FPAA101D or FPAA101H system. So that means you need to use the 2118 systems, in those circumstances. Now it's not always the case. There are some instances where the concession can apply to a FPAA sprinkler protected building, and here they are. D1.3, where you get an extra story before you have to fire-isolate your stair.

If you sprinkler your building, that concession applies for a FPAA 101H system but not the D system. Same for D1.12, where your non-required stairway, ramp or escalator can connect 3 storeys in a sprinkler protected building. D2.21, operation of latch, that is where you have concession from the latch requirements, if your sprinkler system automatically unlocks the door.

Now this one is interesting. It's related to a few other provisions, and that's where the H system is counted, but the D system isn't. So C3.5 and C3.6 which are about automatically closing a fire door when the sprinkler system is activated, the D system doesn't work but the H system does, because a sprinkler relay triggers when water flows through the system after a head activates.

And that's fine, because in your conventional sprinkler system, and in the FPAA 101H system, any water in the system stays still until a sprinkler head is activated. And that's a good time to start the alarm or close the fire doors or unlock the egress doors, and do everything that a building needs to do in fire mode.

However, your FPAA 101D system looks like this. Within each SOU, the system supplies a toilet cistern. This is how the system is tested when the toilet doesn't work, the owner or the tenant calls a plumber, the plumber comes to find the problem and finds the problem in the sprinkler system. Now this means there is always going to be water flowing through the system. And so, we don't want the exit doors to unlock every time somebody flushes the toilet.

So that's why the D system isn't used for the D2.21 concession. It does apply to the concession for fire hydrants, where you can place your hydrant within 10m of a building which has been sprinkler protected. But in Spec E2.2 Clause 3, last example there, only the H system works for that concession, where you don't need an alarm in the kitchen or corridor if you have a sprinkler.

Over in Clauses 4 and 5, neither sprinkler types apply in lieu of smoke detectors. Of course, specification E1.5a Clause 3 has concessions that do apply for the D and H systems, such as reduced FRLs and increased travel distances. Now, before I leave this slide, I want to say that this is not an exhaustive list.

There are plenty of examples in the NCC where there's a red cross in both columns, for instance in C2.6, related to spandrel protection when you don't have to have spandrels if your building is sprinkler protected.

Neither the D or H systems work for that concession. What this list is showing you, is where either the D or H systems are acceptable in the Deemed-to-Satisfy Provisions for the purposes of a concession or provision.

So the take home message is to understand the FPAA systems are unique sprinkler systems, and so are treated differently from the traditional 2118 systems. Which is why your carpet in the units needs to have a critical radiant flux of 2.2 kilowatts per square metre or better, if you have a FPAA system.