Roof Deck Building Codes & Rules

- Roof Deck Tools™ simplifies the National Construction Code (NCC) with interactive graphics, including deemed to comply & best practices.

Fall

Localised Fall

AS 3740:2021, 2.3.1

≥ 1:100^{AS 3740:2021, 2.3.1}

AS/NZS 3500.3:2021, M.12 (a) (i)

1:60^{AS/NZS 3500.3:2021, M.12 (a) (i)}

AS/NZS 3500.2:2021, 10.2.1

≤ 1.2m^{AS/NZS 3500.2:2021, 10.2.1}

AS/NZS 3500.3:2021, 6.3.4

≥ 1:100^{AS/NZS 3500.3:2021, 6.3.4}

AS/NZS 3500.3:2021, M.12 (a) (i)

1:60^{AS/NZS 3500.3:2021, M.12 (a) (i)}

AS 3740:2021, 2.3.1

≥ 1:100^{AS 3740:2021, 2.3.1}

Overlap

Column

Substrate

Sheet Membrane

Localised Fall

Fall

Downpipes

Compatible materials^[1]
Securely attached^[2]
Spacing depending on material^[3]
As close as possible to supporting structure^[4]
Clearance from any electrical, gas pipes & pipeworks^[5]
Access provided^[6]
Clear of any structural elements^[7]

Water & Air TESTING

NCC 2022 V1

All Building Classes

NCC 2022 F1D3, H2D2, H2D6, & HP7.4

[2019 F1.1, 3.1.3.0 - 3.1.3.1, 3.5.1 - 3.5.5]

May 2023

AS/NZS 3500.3:2021, 9.4.1

AS/NZS 3500.3:2021, 9.4.2

NCC 2022 Vol 1, F1D3

NCC 2022 Vol 2, H2D2

NCC 2022 Vol 2, H2D6

NCC 2022 HP, 7.4

Drainage Systems compliance to the NCC^{AS/NZS 3500.3:2021, 9.4.1AS/NZS 3500.3:2021, 9.4.2NCC 2022 Vol 1, F1D3NCC 2022 Vol 2, H2D2}
Water Test^{NCC 2022 Vol 2, H2D6}
Head of water ≤ 3m
Seal all openings except the top
Fill with water to the highest level of the section
Maintain water at level
10 minutes for clay drains
5 minutes for other materials
Air Test^{NCC 2022 HP, 7.4}
30kPa pressure to the drain for 3 minutes
Measure the time it takes for the pressure to drop from 25kPa to 20kPa

Metal or PVC Pipes PROS & CONS

NCC 2022 V1

Metal pipes
Durable but can corrode over time
UV resistant
Heavy weight
Expensive
PVC Pipes
Light weight
Easier to work with and replaceable
Non-durable since they deform permanently with extreme weather changes
Less costly

Metal or PVC Pipes PROS & CONS

NCC 2022 V1

Metal pipes
Durable but can corrode over time
UV resistant
Heavy weight
Expensive
PVC Pipes
Light weight
Easier to work with and replaceable
Non-durable since they deform permanently with extreme weather changes
Less costly

Downpipes INSTALLATION

NCC 2022 V1

All Building Classes

NCC 2022 F1D3, H2D2, H2D6, & HP7.4

[2019 F1.1, 3.1.3.0 - 3.1.3.1, 3.5.1 - 3.5.5]

May 2023

NCC 2022 Vol 1, F1D3

NCC 2022 Vol 2, H2D2

NCC 2022 Vol 2, H2D6

NCC 2022 HP, 7.4

AS/NZS 3500.3:2021, 4.5.6 (a)

AS/NZS 3500.3:2021, 4.5.6 (b)

Drainage Systems to comply to the NCC^{NCC 2022 Vol 1, F1D3NCC 2022 Vol 2, H2D2NCC 2022 Vol 2, H2D6NCC 2022 HP, 7.4}
Location^{AS/NZS 3500.3:2021, 4.5.6 (a)}
Should not interfere with windows, doors, or any access of the building
As close as possible to supporting structure
≥ 100mm clearance from any electrical or gas pipes
≥ 50mm clearance from any pipework or service
Access^{AS/NZS 3500.3:2021, 4.5.6 (b)}
Provide access for inspection
Installation complying with manufacturer recommendation
Seams and joints watertight
Clear of any structural elements
Not concealed in any dry wall to maintain structural integrity of the wall

Downpipes SUPPORT

NCC 2022 V1

All Building Classes

NCC 2022 F1D3, H2D2, H2D6, & HP7.4

[2019 F1.1, 3.1.3.0 - 3.1.3.1, 3.5.1 - 3.5.5]

May 2023

AS/NZS 3500.3:2021, 4.9.6.2

AS/NZS 3500.3:2021, 4.9.2

NCC 2022 Vol 1, F1D3

NCC 2022 Vol 2, H2D2

NCC 2022 Vol 2, H2D6

NCC 2022 HP, 7.4

Drainage Systems to comply to the NCC^{AS/NZS 3500.3:2021, 4.9.6.2AS/NZS 3500.3:2021, 4.9.2NCC 2022 Vol 1, F1D3NCC 2022 Vol 2, H2D2}
System^{NCC 2022 Vol 2, H2D6}
Materials compatible with Roof Drainage System
Securely attached to building structure to prevent movements
No other service attached
protected against corrosion
Spacing^{NCC 2022 HP, 7.4}
≤ 2000mm for aluminium alloys downpipes
≤ 3000mm for cast iron, ductile cast iron, copper, copper alloys, galvanized and stainless steel downpipes
≤ 4000mm for FRC & GRP downpipes
AS 2032 compliant for PVC downpipes
AS 2033 compliant for PE downpipes

Metal or PVC Pipes PROS & CONS

NCC 2022 V2

Metal pipes
Durable but can corrode over time
UV resistant
Heavy weight
Expensive
PVC Pipes
Light weight
Easier to work with and replaceable
Non-durable since they deform permanently with extreme weather changes
Less costly

AS/NZS 3500.3:2021, 2.2

AS/NZS 3500.3:2021, 4.9.2 (b)

AS/NZS 3500.3:2021, 4.9.6.2

AS/NZS 3500.3:2021, 4.5.6 (a) (iii)

AS/NZS 3500.3:2021, 4.5.6 (b) (iii) (A)

AS/NZS 3500.3:2021, 4.5.6 (d)

AS/NZS 3500.3:2021, 6.2.6

Compatible materials^{AS/NZS 3500.3:2021, 2.2}
Securely attached^{AS/NZS 3500.3:2021, 4.9.2 (b)}
Spacing depending on material^{AS/NZS 3500.3:2021, 4.9.6.2}
As close as possible to supporting structure^{AS/NZS 3500.3:2021, 4.5.6 (a) (iii)}
Clearance from any electrical, gas pipes & pipeworks^{AS/NZS 3500.3:2021, 4.5.6 (b) (iii) (A)}
Access provided^{AS/NZS 3500.3:2021, 4.5.6 (d)}
Clear of any structural elements^{AS/NZS 3500.3:2021, 6.2.6}

Insulation

Core Material^[1]
20mm to 300mm thickness
R-Value 1.4 to 9m²K/W

Anti-Condensation BEST PRACTICE

NCC 2022 V1

Anti-Condensation BEST PRACTICE

NCC 2022 V1

To prevent condensation on the underside of the slab due to the different air temperatures inside and outside the building
Reflective foil backed anti-condensation shall be provided
Mechanically fixed to the underside of the soffit

Anti-Condensation BEST PRACTICE

NCC 2022 V1

To prevent condensation on the underside of the slab due to the different air temperatures inside and outside the building
Reflective foil backed anti-condensation shall be provided
Mechanically fixed to the underside of the soffit

Insulation Core MATERIALS

NCC 2022 V1

All Building Classes

NCC 2022 J4D3 & Part 13.2.2 [2019 J1.2, 3.12.1.1]

May 2023

NCC 2022 Vol 1, J4D3 (1)

NCC 2022 HP, 13.2.2 (1)

HB 39:2015, B2.1

Building Insulation compliance to the NCC^{NCC 2022 Vol 1, J4D3 (1)NCC 2022 HP, 13.2.2 (1)}
Insulation Material^{HB 39:2015, B2.1}
20mm to 300mm thickness
R-Value 1.4 to 9m²K/W
Expanded polystyrene
Phenolic modified expanded polystyrene
Polyurethane
Polyisocyanurate
Mineral fibre

Insulation RULES

NCC 2022 V3

Class 1 & 10a

NCC 2022 Part 13.2.2 [2019: 3.12.1.1]

May 2023

NCC 2022 HP, 13.2.2

Insulation Installation^{NCC 2022 HP, 13.2.2}
Abuts or overlaps adjoining Insulation
Continuous Barrier
Fit firmly between supporting members
Maintain specified thickness
Installation should not interfere with safety or performance of services & fittings

HB 39:2015, B2.1

Core Material^{HB 39:2015, B2.1}
20mm to 300mm thickness
R-Value 1.4 to 9m²K/W

Substrate

Smooth, clean, dry & dust free surface^[1]

Substrate PREPARATION

NCC 2022 V1

Falls formed in the substrate directing water towards FW
≥ 1 : 80 fall to shower area
Class 2 concrete finish
Well compacted
Rounded / arrised / filleted edges
No sharp edges, no back of the shovel finish, no un-vibrated areas

Substrate FALLS

NCC 2022 V1

All Building Classes

NCC 2022 F1D5, H2D8, & HP10.2 [2019 F1.4, 3.8.1.2, 3.8.1.3]

May 2023

NCC 2022 Vol 1, F1D5

NCC 2022 Vol 2, H2D8

NCC 2022 HP, 10.2.1

AS 4654.2:2012, 2.5.2

Building elements in Wet Areas to be Waterproof or Water Resistant to the NCC^{NCC 2022 Vol 1, F1D5NCC 2022 Vol 2, H2D8NCC 2022 HP, 10.2.1}
≥ 1 : 100 fall required approaching Floor Waste^{AS 4654.2:2012, 2.5.2}

Substrate PREPARATION

NCC 2022 V1

All Building Classes

NCC 2022 F1D5, H2D8, & HP10.2 [2019 F1.4, 3.8.1.2, 3.8.1.3]

May 2023

NCC 2022 Vol 1, F1D5

NCC 2022 Vol 2, H2D8

NCC 2022 HP, 10.2.1

AS 4654.2:2012, 2.5.3.1

Building elements in Wet Areas to be Waterproof or Water Resistant to the NCC^{NCC 2022 Vol 1, F1D5NCC 2022 Vol 2, H2D8NCC 2022 HP, 10.2.1}
All surfaces to be prepared for Waterproofing System adhesion^{AS 4654.2:2012, 2.5.3.1}
Smooth, dust-free, clean & dry surface
Fill voids
Grind smooth any protrusions
Free of formwork deformity
Prime substrate to prohibit pin-holing during the membrane curing process
Moisture test & apply primer as per Manufacturer's Recommendations

Substrate PREPARATION

NCC 2022 V1

Substrate PREPARATION

NCC 2022 V1

Falls formed in the substrate directing water towards FW
≥ 1 : 80 fall to shower area
Class 2 concrete finish
Well compacted
Rounded / arrised / filleted edges
No sharp edges, no back of the shovel finish, no un-vibrated areas

AS 4654.2:2012, 2.5.3.1

Smooth, clean, dry & dust free surface^{AS 4654.2:2012, 2.5.3.1}

Floor Waste

Membrane connected to the stormwater drainage system^[1]
Sump, inlet pit, grate, or cage installed to minimise debris blockage^[2]

Water Collection BEST PRACTICE

NCC 2022 V1

Water Collection BEST PRACTICE

NCC 2022 V1

Water collected either by dishing the entire area to a drain point or by falling into a gutter
Drain central located
Shorter falls
Less slab thickness required to form falls
Gutter controlling the direction of the water flow towards drain point

Membrane CONNECTION

NCC 2022 V2

All Building Classes

NCC 2022 F1D5, H2D8, & HP10.2 [2019 F1.4, 3.8.1.2, 3.8.1.3]

May 2023

AS 4654.2:2012, 2.10

NCC 2022 Vol 1, F1D5

NCC 2022 Vol 2, H2D8

NCC 2022 HP, 10.2.1

Building elements in Wet Areas to be Waterproof or Water Resistant to the NCC^{AS 4654.2:2012, 2.10NCC 2022 Vol 1, F1D5NCC 2022 Vol 2, H2D8}
Membrane to Drain Connection^{NCC 2022 HP, 10.2.1}
Membrane connected to the stormwater drainage system
Turndown into the inlet system, or
Membrane clamped or attached to a flange connection
Flange part of the inlet into the stormwater system or a separate item fitted on site
Sump, inlet pit, grate, or cage installed to minimise debris blockage
Inlet level should allow substrate drainage at membrane level

Water Collection BEST PRACTICE

NCC 2022 V1

Water collected either by dishing the entire area to a drain point or by falling into a gutter
Drain central located
Shorter falls
Less slab thickness required to form falls
Gutter controlling the direction of the water flow towards drain point

AS 4654.2:2012, 2.10

Membrane connected to the stormwater drainage system^{AS 4654.2:2012, 2.10}
Sump, inlet pit, grate, or cage installed to minimise debris blockage^{AS 4654.2:2012, 2.10}

Membrane

Seaming & adhesion according to membrane type^[1]
Connected to Stormwater Drainage^[2]
Exposed & Protected System^[3]

Membrane SELECTION

NCC 2022 V1

All Building Classes

NCC 2022 F1D5, H2D8, & HP10.2 [2019 F1.4, 3.8.1.2, 3.8.1.3]

May 2023

NCC 2022 Vol 1, F1D5

NCC 2022 Vol 2, H2D8

NCC 2022 HP, 10.2.1

AS 4654.1:2012, 1.5 (a)

AS 4654.1:2012, 1.5 (b)

Building elements in Wet Areas to be Waterproof or Water Resistant to the NCC^{NCC 2022 Vol 1, F1D5NCC 2022 Vol 2, H2D8NCC 2022 HP, 10.2.1}
Exposed system^{AS 4654.1:2012, 1.5 (a)}
Designed to be exposed to weather, mechanical or chemical damage
Protected system^{AS 4654.1:2012, 1.5 (b)}
Designed to be protected from weather, mechanical or chemical damage

Laying Membrane Lap RULES

NCC 2022 V1

All Building Classes

NCC 2022 F1D5, H2D8, & HP10.2 [2019 F1.4, 3.8.1.2, 3.8.1.3]

May 2023

NCC 2022 Vol 1, F1D5

NCC 2022 Vol 2, H2D8

NCC 2022 HP, 10.2.1

AS 4654.2:2012, 2.6.1

Building elements in Wet Areas to be Waterproof or Water Resistant to the NCC^{NCC 2022 Vol 1, F1D5NCC 2022 Vol 2, H2D8NCC 2022 HP, 10.2.1}
Seaming & adhesion according to membrane type^{AS 4654.2:2012, 2.6.1}
Bituminous sheet membrane
≥ 70mm side laps bonded
≥ 150mm end laps staggered & bonded
Synthetic rubber
Factory vulcanized joints
≥ 40mm overlapped
Field joints
≥ 50mm overlapped on side laps &
≥ 100mm on staggered end laps
Flexible polymer sheet
Welded seams
≥ 40mm overlapped
Field welded joints for insulation board
≥ 100mm overlapped &
≥ 75mm for other instances
≥ 100mm wide overlapping tape for all joining with end laps staggered

AS 4654.2:2012, 2.6

AS 4654.2:2012, 2.10

AS 4654.2:2012, 1.5

Seaming & adhesion according to membrane type^{AS 4654.2:2012, 2.6}
Connected to Stormwater Drainage^{AS 4654.2:2012, 2.10}
Exposed & Protected System^{AS 4654.2:2012, 1.5}

Acoustic Insulation

Service not chased into separation walls^[1]
Access required if installed into a separation wall^[2]

Sound Insulation RATINGS

NCC 2022 V2

All Building Classes

NCC 2022 F7D7 [2019 F5.6]

May 2023

NCC 2022 Vol 1, F7D7

Must be separated from the rooms if passing through more than one SOU^{NCC 2022 Vol 1, F7D7}
Rw + Ctr 40 if adjacent room is habitable
Rw + Ctr 25 if adjacent room is non-habitable or a kitchen

Downpipes ACOUSTIC

NCC 2022 V2

Class 1 & 10a

NCC 2022 10.7.4 [2019 3.8.6.5]

May 2023

NCC 2022 HP, 10.7.4 (1)

NCC 2022 HP, 10.7.4 (2)

Service not chased into concrete or masonry separation walls^{NCC 2022 HP, 10.7.4 (1)}
If installed into a separation wall a door or panel is required for access^{NCC 2022 HP, 10.7.4 (2)}
Not in habitable rooms
Firmly fixed with frame or rebate overlap ≥ 10mm
≥ 33mm wood, plasterboard, or blockboard
≥ 9mm compressed fibre reinforced cement sheeting
24.4kg/m² for other suitable materials

NCC 2022 HP, 10.7.4 (1)

NCC 2022 HP, 10.7.4 (2) (a)

Service not chased into separation walls^{NCC 2022 HP, 10.7.4 (1)}
Access required if installed into a separation wall^{NCC 2022 HP, 10.7.4 (2) (a)}