NCC answers library · DatumDesk

WAClass 1NCC 2025 (NCC 2022 electable)8 Oct 2026
Our Bunbury bathroom has a full-height window beside the bath and a glass shower screen. The glazier says ordinary annealed glass is fine for the window because it is not a door. When does bathroom glazing have to be safety glass?
The glazier is wrong. In a bathroom, the safety glazing rule is triggered by height, not by whether the glass is a door: any glazing, including windows, with its lowest sight line less than 2.0 m above the floor, the bottom of the bath or the shower base must be safety glass. A full-height window beside a bath is caught, and so is the shower screen.
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SAClass 1NCC 2022 (NCC 2025 from 1 May 2027)8 Oct 2026
Our Adelaide brick veneer house on a reactive clay site has long unbroken walls, and the engineer flagged articulation joints. How far apart do articulation joints need to be in masonry veneer, and what sets the spacing?
The engineer is right. On a reactive clay site articulation joints are mandatory, because the only exemption is for soil classes A and S. Spacing is not set by the soil class: it is set by the wall, at not more than 6 m centres for walls without large openings and not more than 5 m centres where openings exceed 900 mm x 900 mm, plus joints at specific changes in the wall.
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VICClass 1NCC 202529 Sept 2026
The building surveyor flagged the timber stair off our Geelong deck for slip resistance on the treads and nosings. What classification do external stair treads need, and does a nosing strip get us out of treating the whole tread?
The surveyor is right to raise it. A stair exposed to the weather is a wet surface, so treads need P4 or R11 when tested to AS 4586. A tested nosing strip rated P4 is a genuine alternative to treating the whole tread, but the strip itself must carry that classification.
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NSWClass 1NCC 202229 Sept 2026
Our two-storey Sydney house has bedrooms upstairs and the living areas downstairs. The certifier wants an extra smoke alarm on the lower floor even though there are no bedrooms there. Where do smoke alarms have to go in a new Class 1a house, and do they need to be interconnected?
The certifier is right. In a Class 1a house every storey needs a smoke alarm, including a storey with no bedrooms, and once there is more than one alarm they must all be interconnected, mains powered where mains power is supplied, and comply with AS 3786.
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VICClass 5NCC 202529 Sept 2026
The landlord says our Melbourne office fitout for 60 staff can rely on the base building's toilets a floor below. The building surveyor isn't convinced. How many sanitary facilities does a Class 5 tenancy need?
On a 30 and 30 split, 60 staff need 2 closet pans, 2 urinals and 1 washbasin for men and 2 closet pans and 1 washbasin for women, plus an accessible unisex compartment on every storey with sanitary compartments. Whether the base-building toilets a floor below can supply that count is a separate question the surveyor should tie to a named clause.
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NSWClass 2NCC 2022 (with the Design and Building Practitioners Act 2020)29 Sept 2026
We are the architects on a three-storey apartment building in Parramatta. The builder wants to swap our balcony waterproofing detail for a cheaper system on site. Under the Design and Building Practitioners Act, does that need a new regulated design, and who has to declare it?
Yes. Waterproofing is a building element under the Act, so the swap is a variation to a regulated design: before the varied work starts, a registered design practitioner must prepare the varied design and a fresh design compliance declaration must be obtained, and the builder carries the duty to make that happen.
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QLDClass 1NCC 2022 (with QDC MP 4.4)29 Sept 2026
Our Brisbane infill site is mapped as noise category 2 under the transport noise corridor rules. The acoustic consultant has specified glazing, but the architect wants bigger bedroom windows. What ratings does the envelope need, and does window size change the glazing requirement?
Yes, window size matters. At Noise Category 2 the glazing to a habitable room needs Rw 32 while the room's total glazing is 1.8 m² or less, and Rw 35 once it goes over 1.8 m², so bigger bedroom windows can push the specification up a band.
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VICClass 1NCC 202529 Sept 2026
Our Bendigo design has the laundry door opening straight onto a four-riser external stair down to the yard. The building surveyor wants a landing at the door. When is a threshold landing required, and how big does it need to be?
The building surveyor is right. A doorway that opens onto a stair of more than 3 risers or more than 570 mm needs a threshold landing at least 750 mm long, the full width of the doorway, with a gradient no steeper than 1:50.
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WAClass 1NCC 2025 (NCC 2022 electable)27 Sept 2026
Our Perth renovation adds 20 downlights to an insulated ceiling. The energy assessor says we now need thicker insulation to make up for the gaps. Is that a real requirement, and how is the loss worked out?
It is a real rule: where ceiling insulation is cut back for fittings like downlights, the remaining insulation must be lifted to the R-Value in Table 13.2.3w, set by the percentage of ceiling left uninsulated. Whether that table binds a Perth renovation depends on the compliance path, because WA lets alterations to existing homes use a different route.
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SAClass 1NCC 202227 Sept 2026
Our Adelaide Hills staircase turns with three winders, and the certifier says the going is too narrow on the inside. How are goings measured on winders, and is a winder even allowed in a Class 1 house?
Winders are allowed: up to 3 in lieu of a quarter landing, so a three-winder turn is fine in principle. The going is not tested at the narrow inside edge but at the middle of the stair (up to 1 m wide) or 400 mm in from each side (over 1 m wide), and it must be at least 240 mm there.
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QLDClass 1NCC 202227 Sept 2026
Our Toowoomba first-floor balcony has a horizontal-rail balustrade, and the certifier says the rails make it climbable. The drop is about 3 m. What does the code say about climbable elements, and does a solid panel at the bottom fix it?
Not at 3 m, on the deemed-to-satisfy rules: the ban on climbable horizontal elements between 150 mm and 760 mm above the floor only applies where the fall is more than 4 m, measured to the surface beneath. The 125 mm opening and 40 mm edge gap rules still apply, and a solid bottom panel is not a defined fix in the Standard.
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ACTClass 1NCC 2022 (NCC 2025 electable to 30 April 2027)27 Sept 2026
Our Canberra tiler says the new laundry does not need waterproofing because there is no shower in it. The certifier wants the floor treated anyway. What does the code require for a laundry?
The certifier is right. The Housing Provisions treat a laundry as its own wet area: the whole floor must be water resistant and so must the wall/floor junctions, with extra wall and junction treatment where the tub sits against a wall, whether or not there is a shower.
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NSWClass 1NCC 2022 (with Planning for Bush Fire Protection 2019)27 Sept 2026
Our client's site assessment came back BAL-FZ. Is building even feasible at flame zone rating, and can a performance solution get us away from the deemed-to-satisfy requirements?
Building at BAL-FZ is feasible, but in NSW the deemed-to-satisfy route is closed at the flame zone, so a performance solution is the pathway rather than an escape from it, and it should still be built on AS 3959 and the NASH Standard.
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WAClass 1NCC 2025 (NCC 2022 electable)27 Sept 2026
Our Perth two-storey design has the living room window 700 mm off the side boundary, and the only other glazing opens under the covered alfresco. The certifier says the room fails natural light. Does the side window count at all, and does light through the alfresco count?
The side window cannot count: a window providing natural light must be at least 900 mm from an adjoining allotment boundary, so 700 mm is 200 mm short. Glazing under the alfresco can count toward the 10% of floor area needed if the alfresco is an open verandah or the like, and if it is enclosed, the stricter borrowed light test applies instead.
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SAClass 1NCC 202227 Sept 2026
Our Adelaide terrace design has three skylights in a roof that runs to within a metre of the party wall, and the certifier has raised fire separation. How close to a boundary or separating wall can a roof light sit, and how much of the roof can they take up?
The certifier is right to raise it. A combustible roof light must sit at least 900 mm from the vertical projection of a separating wall and 900 mm from a side boundary, and all the roof lights together can take up no more than 20% of the roof or part of the roof.
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QLDClass 1NCC 2022 (with QDC MP 4.2)25 Sept 2026
Our client insists every new Queensland home needs a rainwater tank, but the certifier says it depends on the council. What does the code actually require?
The certifier is right. A tank is only mandatory for a new Queensland house where the council holds a Ministerial approval making QDC MP 4.2 apply to its area, and even then a greywater plant or other supplementary supply can meet the requirement instead.
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TASClass 1NCC 202225 Sept 2026
We want to turn a Hobart attic into a bedroom. The ceiling is 2.4 m at the ridge but rakes down steeply on both sides. The designer says it can still comply. How is ceiling height measured under a sloping roof?
An attic bedroom needs at least 2.2 m of ceiling height over two-thirds of its floor area, with anything under 1.5 m left out of the count. A ceiling that rakes straight down from a 2.4 m ridge gets nowhere near that, so the designer is only right if the ceiling has a flat section or a different profile.
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ACTClass 1aNCC 2025 (electable in the ACT to 30 April 2027)25 Sept 2026
Our sloping Canberra block makes a step-free entry very hard. The certifier mentioned the livable housing provisions have an out for exactly this. When is step-free entry required and what relief exists?
The certifier is right that there is an exemption, but it has two limbs and you need both: no step-free route via a garage, carport or parking space, and a site condition such as an average slope steeper than 1:14. It only switches off the access path clause; everything else in the Livable Housing Design Standard still applies.
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WAClass 1NCC 2025 (NCC 2022 electable to 30 April 2027)21 Sept 2026
Our Perth duplex permit application goes in around March 2027. Can we still elect NCC 2022, and what should we watch as the 1 May 2027 cutoff approaches?
Yes: WA reg 31A(2)(b) lets a permit applicant use the edition in effect 12 months before the application, which for a March 2027 lodgement is NCC 2022, but the option runs out for applications made from 1 May 2027.
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QLDClass 1aNCC 202221 Sept 2026
Our deck on a sloping Brisbane block sits 800 mm above ground at the house and about 1.3 m at the far corner. The certifier wants a barrier the whole way round. Where exactly does the 1 m trigger bite?
The 1 m fall test is measured at each point along the deck edge, not across the deck as a whole, so a barrier is required along the far sections and not at the 800 mm house end. Ask the certifier to name the clause behind a whole-of-perimeter call.
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VICClass 1aNCC 202521 Sept 2026
Our Ballarat build has the ensuite exhaust fan venting into the roof space. The builder says that's how it's always been done, but the energy assessor disagrees. Do exhaust fans have to duct outside now, and what flow rates apply?
The assessor is right. A bathroom or sanitary compartment exhaust must discharge to outdoor air, not into the roof space, at not less than 25 L/s. The practice was not compliant under NCC 2022 either, and a Victorian Energy Upgrades approved fan does not make it compliant.
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NSWClass 1aNCC 202224 Aug 2026
The certifier flagged that our first-floor bedroom windows need opening restrictors even though the sills are 900 mm above the floor. When do openable bedroom windows need fall protection, and do screens count?
The trigger is the 2 m drop below the window, not the sill height. A 900 mm sill sits under the 1.7 m exemption, so a restrictor or screen is required, and a compliant screen is an accepted alternative to a device.
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ACTClass 2-9NCC 2022 (either-edition window to 2027)19 Aug 2026
Our Canberra project's DA was lodged in October 2026 but the building approval won't land until mid-2027. The certifier says we can still choose NCC 2022. Is that right?
Yes: a DA lodged before 1 November 2026 keeps the ACT either-edition election, so NCC 2022 can still be nominated even where the building approval issues after the 1 May 2027 mandatory-NCC-2025 date, until the DA expires.
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SAClass 1aNCC 2022 + 2025 (split)28 July 2026
We're renovating a bathroom in Adelaide. The builder is working to NCC 2022 but the plumber says his work falls under NCC 2025. Can both be right on the same job?
South Australia is in a split adoption: building work follows NCC 2022 while plumbing and drainage follow NCC 2025, so a builder and a plumber can each be on a different edition of the same renovation.
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TASClass 1aNCC 202228 July 2026
Our Hobart project got its building approval on 20 May 2026, while NCC 2025 was briefly in force in Tasmania. Which edition applies to our project now?
Approvals granted in Tasmania between 1 May and 4 June 2026 sit in a genuine gap: the reinstating Act has no savings clause, so neither edition can be assumed and written CBOS confirmation is the only safe course.
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QLDClass 1aNCC 202223 July 2026
Our certifier says the study doesn't qualify as a habitable room because the window is only 9% of the floor area. How is natural light measured, and can we borrow light from the living room next door?
The 10% natural light rule is measured on light-transmitting area, net of framing, and a shortfall can be fixed three ways: a bigger window, a roof light at 3%, or borrowed light from an adjoining room that is glazed for both rooms combined.
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TASClass 1aNCC 2022 with BCA 2019 Part 3.1223 July 2026
Our energy assessor specified R5.0 ceiling insulation for a climate zone 7 build, but the builder insists R4.0 is enough because the roof has sarking. Who is right?
In Tasmania neither side can rely on the national zone 7 ceiling table. The Tasmanian schedule replaces Housing Provisions Section 13 with BCA 2019 Part 3.12, so the dispute has to be settled against BCA 2019, clause by clause.
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WAClass 1aNCC 202523 July 2026
Our split-level has a short flight of five steps (about 850 mm total rise). The certifier wants a handrail on the main stairs but not there. Is that right?
Yes: a flight with a change in elevation under 1 m is exempt from the handrail requirement, while the main stairs need one on at least one side, continuous, at 865 mm or more above the nosings.
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VICClass 1aNCC 202515 July 2026
I'm building brick veneer in Melbourne and my energy assessor says the walls need a drained and ventilated cavity. Is that right, and what exactly does it involve?
The assessor is right: in climate zone 6 a masonry veneer wall must have a drained and ventilated cavity at least 12 mm deep with 1,000 mm2 per metre of openings, and the requirement comes from condensation management, not the energy provisions.
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NSWClass 1aNCC 202214 July 2026
How high does waterproofing need to extend on shower walls, and does the whole bathroom floor need to be waterproofed?
Shower walls must be waterproof to at least 1800 mm above the floor substrate. The rest of the bathroom floor usually only needs to be water resistant, with one waterstop-related exception worth knowing.
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SAAll classesNCC 20259 July 2026
What is the maximum hot water delivery temperature at a bathroom basin or shower?
Heated water must be delivered at no more than 50 °C at a standard bathroom fixture, dropping to 45 °C in aged care, health care, schools and other high scald-risk settings. In SA this is already an NCC 2025 question.
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WAClass 1aNCC 20259 July 2026
How high does a balustrade need to be on a deck or balcony, and when is one required at all?
A barrier is required wherever a fall of 1 m or more is possible, built to at least 1 m high on a deck or landing and 865 mm above stair nosings, with a 125 mm sphere rule for openings.
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TASClass 1aNCC 20229 July 2026
What are the maximum riser and minimum going dimensions for stairs in a new house?
For a standard stairway in a Class 1a home the riser can be at most 190 mm and the going at least 240 mm, with the 2R+G slope relationship kept between 550 and 700 mm.
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NSWClass 1aNCC 202230 June 2026
Our Sydney loft conversion has a raked ceiling, and the certifier says the new bedroom doesn't meet the 2.4 m ceiling height. How is height measured under a sloping ceiling, and what applies over the stair?
Under a sloping ceiling the required height only has to be met over two-thirds of the floor area, after excluding anything lower than 1.5 m, and a habitable room in an attic needs 2.2 m rather than 2.4 m. Over a stair the minimum is 2.0 m, not 2.1 m.
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VICClass 1aNCC 202527 June 2026
We're building a double-storey home in Geelong with bedrooms on both levels. Where exactly do the smoke alarms have to go, and do they all need to be interconnected?
Every storey needs a smoke alarm, plus one serving each hallway or group of bedrooms, all complying with AS 3786, mains powered and interconnected so they sound together. On the ceiling they sit at least 300 mm from the wall, or 500 to 1500 mm from the apex of a sloping ceiling.
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QLDClass 1aNCC 202226 June 2026
We're designing a new home in Brisbane and the client has heard it has to hit 7 stars. Is that right, and is there any concession for a Queensland climate?
Seven stars, with separate heating and cooling load limits, is one Deemed-to-Satisfy pathway, not the only one. In climate zones 1 and 2 a covered outdoor living area brings the minimum down to 6.5 stars, or 6 stars with a ceiling fan, and a separate whole-of-home energy requirement applies on top.
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Cited NCC compliance answers, in plain English.

Our Bunbury bathroom has a full-height window beside the bath and a glass shower screen. The glazier says ordinary annealed glass is fine for the window because it is not a door. When does bathroom glazing have to be safety glass?

Our Adelaide brick veneer house on a reactive clay site has long unbroken walls, and the engineer flagged articulation joints. How far apart do articulation joints need to be in masonry veneer, and what sets the spacing?

The building surveyor flagged the timber stair off our Geelong deck for slip resistance on the treads and nosings. What classification do external stair treads need, and does a nosing strip get us out of treating the whole tread?

Our two-storey Sydney house has bedrooms upstairs and the living areas downstairs. The certifier wants an extra smoke alarm on the lower floor even though there are no bedrooms there. Where do smoke alarms have to go in a new Class 1a house, and do they need to be interconnected?

The landlord says our Melbourne office fitout for 60 staff can rely on the base building's toilets a floor below. The building surveyor isn't convinced. How many sanitary facilities does a Class 5 tenancy need?

We are the architects on a three-storey apartment building in Parramatta. The builder wants to swap our balcony waterproofing detail for a cheaper system on site. Under the Design and Building Practitioners Act, does that need a new regulated design, and who has to declare it?

Our Brisbane infill site is mapped as noise category 2 under the transport noise corridor rules. The acoustic consultant has specified glazing, but the architect wants bigger bedroom windows. What ratings does the envelope need, and does window size change the glazing requirement?

Our Bendigo design has the laundry door opening straight onto a four-riser external stair down to the yard. The building surveyor wants a landing at the door. When is a threshold landing required, and how big does it need to be?

Our Perth renovation adds 20 downlights to an insulated ceiling. The energy assessor says we now need thicker insulation to make up for the gaps. Is that a real requirement, and how is the loss worked out?

Our Adelaide Hills staircase turns with three winders, and the certifier says the going is too narrow on the inside. How are goings measured on winders, and is a winder even allowed in a Class 1 house?

Our Toowoomba first-floor balcony has a horizontal-rail balustrade, and the certifier says the rails make it climbable. The drop is about 3 m. What does the code say about climbable elements, and does a solid panel at the bottom fix it?

Our Canberra tiler says the new laundry does not need waterproofing because there is no shower in it. The certifier wants the floor treated anyway. What does the code require for a laundry?

Our client's site assessment came back BAL-FZ. Is building even feasible at flame zone rating, and can a performance solution get us away from the deemed-to-satisfy requirements?

Our Perth two-storey design has the living room window 700 mm off the side boundary, and the only other glazing opens under the covered alfresco. The certifier says the room fails natural light. Does the side window count at all, and does light through the alfresco count?

Our Adelaide terrace design has three skylights in a roof that runs to within a metre of the party wall, and the certifier has raised fire separation. How close to a boundary or separating wall can a roof light sit, and how much of the roof can they take up?

Our client insists every new Queensland home needs a rainwater tank, but the certifier says it depends on the council. What does the code actually require?

We want to turn a Hobart attic into a bedroom. The ceiling is 2.4 m at the ridge but rakes down steeply on both sides. The designer says it can still comply. How is ceiling height measured under a sloping roof?

Our sloping Canberra block makes a step-free entry very hard. The certifier mentioned the livable housing provisions have an out for exactly this. When is step-free entry required and what relief exists?

Our Perth duplex permit application goes in around March 2027. Can we still elect NCC 2022, and what should we watch as the 1 May 2027 cutoff approaches?

Our deck on a sloping Brisbane block sits 800 mm above ground at the house and about 1.3 m at the far corner. The certifier wants a barrier the whole way round. Where exactly does the 1 m trigger bite?

Our Ballarat build has the ensuite exhaust fan venting into the roof space. The builder says that's how it's always been done, but the energy assessor disagrees. Do exhaust fans have to duct outside now, and what flow rates apply?

The certifier flagged that our first-floor bedroom windows need opening restrictors even though the sills are 900 mm above the floor. When do openable bedroom windows need fall protection, and do screens count?

Our Canberra project's DA was lodged in October 2026 but the building approval won't land until mid-2027. The certifier says we can still choose NCC 2022. Is that right?

We're renovating a bathroom in Adelaide. The builder is working to NCC 2022 but the plumber says his work falls under NCC 2025. Can both be right on the same job?

Our Hobart project got its building approval on 20 May 2026, while NCC 2025 was briefly in force in Tasmania. Which edition applies to our project now?

Our certifier says the study doesn't qualify as a habitable room because the window is only 9% of the floor area. How is natural light measured, and can we borrow light from the living room next door?

Our energy assessor specified R5.0 ceiling insulation for a climate zone 7 build, but the builder insists R4.0 is enough because the roof has sarking. Who is right?

Our split-level has a short flight of five steps (about 850 mm total rise). The certifier wants a handrail on the main stairs but not there. Is that right?

I'm building brick veneer in Melbourne and my energy assessor says the walls need a drained and ventilated cavity. Is that right, and what exactly does it involve?

How high does waterproofing need to extend on shower walls, and does the whole bathroom floor need to be waterproofed?

What is the maximum hot water delivery temperature at a bathroom basin or shower?

How high does a balustrade need to be on a deck or balcony, and when is one required at all?

What are the maximum riser and minimum going dimensions for stairs in a new house?

Our Sydney loft conversion has a raked ceiling, and the certifier says the new bedroom doesn't meet the 2.4 m ceiling height. How is height measured under a sloping ceiling, and what applies over the stair?

We're building a double-storey home in Geelong with bedrooms on both levels. Where exactly do the smoke alarms have to go, and do they all need to be interconnected?

We're designing a new home in Brisbane and the client has heard it has to hit 7 stars. Is that right, and is there any concession for a Queensland climate?

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