Since NCC 2019, a new mid-rise Class 2 or 3 building — four or more storeys, not more than 25 m effective height — must have automatic sprinklers under the Deemed-to-Satisfy path. The Code does not insist that every one of those buildings be a full AS 2118.1 install. It offers a short menu.
That menu is why so many apartment and hotel conversations now sound like an alphabet: FPAA101D, FPAA101H, AS 2118.4, and the conventional AS 2118.1. They are not interchangeable stickers. They take water from different places, they stop at different building shapes, and they unlock different concessions.
This comparison is for owners, project managers and designers who have to pick one before the hydraulic consultant sizes a tank. It sits in standards and compliance. Cost ranges in Australian dollars belong in how much fire sprinklers cost; what follows is the regulatory and water-supply logic that makes one option cheap and another impossible.
What is FPAA101D?
FPAA101D is a Fire Protection Association Australia technical specification: Automatic fire sprinkler system design and installation — Domestic water supply. The NCC adopted it so that a mid-rise residential building could be sprinkled from the drinking-water pipework that the building already needs.
That is the whole idea. Residents run showers and taps every day, so the water supply is, in a rough sense, continuously proved. The specification is written around WaterMark products rather than a dedicated fire-service pump room. Heads are still automatic sprinklers. The system is still throughout the building. It is not a glorified tap.
The ABCB’s 2019 regulatory-impact material treated FPAA101D as the cheapest of the mandated options. On the published six-storey hotel test case, a 101D building with its concessions came out about 1.7 per cent cheaper than the old unsprinklered NCC 2016 DTS design. That is a Board talking point, not a tender. It does tell you why developers reach for 101D first.
What 101D can do, when the Code lets it:
- protect a pure Class 2 or 3 mid-rise building that is not residential care
- use the domestic water service, often without a dedicated sprinkler tank
- support the Specification 18 concession set written for 101D, including travel-distance relief and, in defined cases, internal-hydrant relief
What 101D cannot do, even if someone has already printed the brochure:
- serve as a home standard on a Class 1a house (that is AS 2118.5)
- serve residential care buildings
- survive every mixed-use building. Specification 17 blocks 101D where the non-residential parts (Class 4, 5, 6, 7, 8, 9a or 9b) run to more than two storeys, take more than 25 per cent of the floor area, or sit above the fourth storey
- cover a Class 7a car park, other than open-deck, that holds more than 40 vehicles — and Fire and Rescue NSW reads that as vehicles in the building, not in one compartment
- invent town-main pressure that is not there. A weak street main kills the cost case as surely as a tank does
Fire services also treat 101D as the lightest of the four options. In a mixed-class building that still legally allows 101D, FRNSW has recommended 101H or better because the Specification 18 concessions, including dry internal hydrants, do not apply to multiple classifications. Cheap and legal are not the same as cheap and liked.
How does FPAA101H differ from a domestic-water system?
FPAA101H is the sibling specification: Automatic fire sprinkler system design and installation — Hydrant water supply. The sprinklers take water from the hydrant service, not from the kitchen tap riser.
That single change has three consequences.
First, the water supply is a fire water supply. It is designed, boosted and proved as fire water. You lose the “the showers already test it” story, and you usually pick up hydrant pipe, a booster and the arguments that come with hydrants versus hose reels.
Second, the ABCB’s test-case cost sat between 101D and a full AS 2118 system — about 3.2 per cent dearer than the old unsprinklered DTS hotel, against 4.6 per cent for AS 2118.1 or AS 2118.4. Again, those are regulatory-impact percentages, useful as a ranking, useless as a quote.
Third, 101H is the option fire services often prefer once the building is no longer a simple residential box. It still cannot be used for residential care, and it still cannot be used with a large enclosed car park above the 40-vehicle mark. It can be used in more mixed-use shapes than 101D, subject to Specification 17.
Is 101H “better” than AS 2118.4? Only if you mean better matched to a five- or six-storey building that already has a hydrant main. AS 2118.4 is a Standard with a four-storey ceiling. 101H is a specification written for the mid-rise NCC pathway. Comparing them as if one were a luxury version of the other is how people specify the wrong water supply.
101H still is not AS 2118.1. It does not give you Ordinary Hazard warehouse densities, Extra High / High Hazard process protection, or a system an insurer will automatically treat as a commercial sprinkler installation. If the ground floor becomes a bottle shop with storage, re-read Specification 17 before you assume the 101H sticker still fits.
Where does AS 2118.4 still fit?
AS 2118.4 is Automatic fire sprinkler systems — Sprinkler protection for accommodation buildings not exceeding four storeys in height. It is the older residential Standard, and it is still in the NCC.
Use it when the building is genuinely low-rise residential: a four-storey Class 2 or 3, some Class 9c aged-care buildings, and some Class 9a residential-care buildings where Specification 17 says “AS 2118.4 as applicable”. The Standard’s own scope is the four-storey cap. The NCC can point at Part 4 for care buildings; it cannot stretch Part 4 over a six-storey apartment.
Part 4 is written to keep a room below flashover. Densities, head types and water supplies are residential, not Light Hazard office clones and not High Hazard storage rules. It is a conventional, document-controlled Standard that hydraulic consultants and certifiers already know. That is why some four-storey projects still choose it over 101D even when 101D would be legal: fewer arguments with the surveyor, the insurer and the fire service.
Part 4 is also why “residential sprinkler” is an overloaded phrase. In one meeting it means AS 2118.4. In the next it means 101D. In a third it means a house system under AS 2118.5. Write the number on the fire-safety schedule.
AS 2118.1 remains the default once you leave that residential envelope: effective height over 25 m, more than four storeys where Part 4 does not apply, mixed use that fails the FPAA tests, care buildings the Code sends to Part 1, commercial floors, and any insurer who will not hear of a domestic-water system. It is the dearest of the four on the ABCB ranking and the most conventional.
Which standard should a six-storey apartment use?
Work the decision in this order. Do not start with the brochure.
- Confirm the NCC trigger. A three-storey Class 2 building may not need sprinklers at all. A building over 25 m effective height needs a full-height AS 2118.1 system, not a mid-rise residential spec. See when the NCC requires fire sprinklers.
- Confirm the classification. Pure Class 2 or 3, not care, not a large enclosed car park, non-residential parts within the 101D limits? Then 101D is legally on the table. Add retail, two basement parks and a gym, and it may already be off.
- Confirm the water. Ask the water authority, in writing, what flow and pressure exist at the point of connection and whether they will let you take fire or domestic water at the rate a sprinkler remote area needs. 101D dies on a weak main. 101H and AS 2118.1 then need a tank, a pump, or both.
- Confirm the storey count. Four storeys can still use AS 2118.4. Six storeys cannot. A home standard cannot be scaled to either.
- Price the concessions with the structure, not after it. 101D’s cost case in the ABCB work assumed the travel, FRL and hydrant concessions were actually taken. If the architect has already drawn two extra stairs and 90-minute doors, you have spent the saving.
- Listen to the fire service and the insurer. In New South Wales, published FRNSW positions on mixed-use buildings and Specification 18 concessions are not optional reading. An insurer who prices AS 2118.1 as a credit and 101D as a query will change the net cost.
A worked example, without pretending it is a quote: a six-storey, 22 m, pure Class 2 building on a strong urban main is the 101D poster case. The same building with ground-floor retail, two basement parks holding 70 cars, and a water authority that will not certify the domestic flow is an AS 2118.1 building with tanks, whatever the feasibility report said in week two.
Write the chosen specification on the fire safety schedule or essential-safety-measures list in full — “FPAA101D (Specification 17 and Specification 18)” is a different legal object from “AS 2118.1:2017 Ordinary Hazard”. Maintenance, annual statements and future fit-outs all depend on that line. If you cannot say which standard the building has, you do not yet have a design.