Stiffened Raft Slab Building Codes & Rules
- Stiffened Raft Tools™ simplifies the National Construction Code (NCC) with interactive graphics, including deemed to comply & best practices.
NCC 2022 HP, 4.2.14
AS 2870:2011, 3.2.3
NCC 2022 HP, 4.2.14
AS 2870:2011, 3.2.3
Edge Rebate
Soil Class A, S or M Only
Masonry Veneer
AS 2870:2011, 3.5.4
Construction Joint
- R10/N10 fitment at 600mm CTS intervalsAS 2870:2011, 3.5.4
Beam Spacing
NCC 2022 HP, 4.2.14
AS 2870:2011, 3.2.3
NCC 2022 HP, 4.2.14
AS 2870:2011, 3.2.3
NCC 2022 HP, 4.2.14
AS 2870:2011, 3.2.3
NCC 2022 HP, 4.2.14
AS 2870:2011, 3.2.3
NCC 2022 HP, 4.2.14
AS 2870:2011, 3.2.3
NCC 2022 HP, 4.2.14
AS 2870:2011, 3.2.3
NCC 2022 HP, 4.2.14
AS 2870:2011, 3.2.3
NCC 2022 HP, 4.2.14
AS 2870:2011, 3.2.3
NCC 2022 HP, 4.2.14
AS 2870:2011, 3.2.3
NCC 2022 HP, 4.2.14
AS 2870:2011, 3.2.3
NCC 2022 HP, 4.2.14
AS 2870:2011, 3.2.3
AS 3660.1:2014, 4.4
NCC 2022 HP, 4.2.14
AS 2870:2011, 3.2.3
Brick
Veneer
Loadbearing Wall
Articulated Brickwork
NCC 2022 HP, 4.2.14
AS 2870:2011, 3.2.3
Slab Thickening
Internal Beam
Loadbearing Wall
Timber Frame
Brick Veneer
Fully Sarked
Slab on Ground
Vapor Barrier
Edge Beam
Beam Layout
- Integral structural grid form[1]
- Reinforcement for Edge & Internal Beam [2]
- Varies based on Site Class (A, S, or M)
Beam Layout RULES
NCC 2022 V3
All Building Classes
NCC 2022 HP4.2.14
May 2023
NCC 2022 HP, 4.2.14
NCC 2022 HP, 4.2.14
AS 2870:2011, 5.3.9
NCC 2022 HP, 4.2.14
AS 2870:2011, 3.2.3
- Footings and Slabs must comply with the NCC
- Form an integral structural gridNCC 2022 HP, 4.2.14
- 10% increase in spacing allowedNCC 2022 HP, 4.2.14
- If spacing of opposite direction is ≤ 20% than required
- If with internal beamsAS 2870:2011, 5.3.9
- ≤ 4m from external corner to intersection with next internal beam
- Use Bottom Reinforcement for deeper Beams (see Tables for Site Classes A, S, & M)NCC 2022 HP, 4.2.14AS 2870:2011, 3.2.3
NCC 2022 HP, 4.2.14
NCC 2022 HP, 4.2.14
- Integral structural grid formNCC 2022 HP, 4.2.14
- Reinforcement for Edge & Internal Beam NCC 2022 HP, 4.2.14
- Varies based on Site Class (A, S, or M)
Concrete Benchmark
Concrete Cover
- ≥ 30mm over membrane[1]
- ≥ 40mm unprotected ground[2]
- ≥ 20mm internal surface[3]
- ≥ 40mm external exposure[4]
Concrete COVER
NCC 2022 V3
All Building Classes
NCC 2022 4.2.11 [2019 3.2.3.2]
May 2023
AS 3600:2018, 4.10.3.2
AS 3600:2018, 4.3.1 (c)
- Concrete must comply with the NCC
- Cover for standard Formwork & compaction as per tableAS 3600:2018, 4.10.3.2
- Add thickness where cast against ground
- Embedded elements must be protected from corrosion or deteriorationAS 3600:2018, 4.3.1 (c)
NCC 2022 HP, 4.2.11 (5) (b)
NCC 2022 HP, 4.2.11 (5) (a)
NCC 2022 HP, 4.2.11 (5) (c)
NCC 2022 HP, 4.2.11 (5) (d)
- ≥ 30mm over membraneNCC 2022 HP, 4.2.11 (5) (b)
- ≥ 40mm unprotected groundNCC 2022 HP, 4.2.11 (5) (a)
- ≥ 20mm internal surfaceNCC 2022 HP, 4.2.11 (5) (c)
- ≥ 40mm external exposureNCC 2022 HP, 4.2.11 (5) (d)
Recessed Slab
- Recess depth ≤ Slab thickness
- ≥ 400mm lap length[1]
- Recess depth ≥ Slab thickness
- ≥ 400mm Steel mesh overlap[2]
Recess Depth RULES
NCC 2022 V1
All Building Classes
NCC 2022 HP4.2.22
May 2023
NCC 2022 HP, 4.2.22 (1) (a)
NCC 2022 HP, 4.2.22 (1) (b) (i)
NCC 2022 HP, 4.2.22 (1) (b) (ii)
- If ≤ 1/2 of nominal slab thickness
- ≥ 400mm lap length of reinforcing mesh from inside face of the recessNCC 2022 HP, 4.2.22 (1) (a)
- If ≥ 1/2 of nominal slab thickness
- ≥ 400mm overlap of top & bottom reinforcing meshNCC 2022 HP, 4.2.22 (1) (b) (i)
- 2 layers of SL72 bottom reinforcing meshNCC 2022 HP, 4.2.22 (1) (b) (ii)
NCC 2022 HP, 4.2.22 (1) (a)
NCC 2022 HP, 4.2.22 (1) (b) (i)
- Recess depth ≤ Slab thickness
- ≥ 400mm lap lengthNCC 2022 HP, 4.2.22 (1) (a)
- Recess depth ≥ Slab thickness
- ≥ 400mm Steel mesh overlapNCC 2022 HP, 4.2.22 (1) (b) (i)
Reinforcement
- ≤ 800mm CTS bar chairs spacing[1]
- Firmly fixed & supported off the ground[2]
- Wire chairs with concrete cover & placed on flat bases[3]
Reinforcement RULES
NCC 2022 V1
All Building Classes
NCC 2022 HP4.2.11, HP4.2.14 [2019:3.2.3.2]
May 2023
NCC 2022 HP, 4.2.14
NCC 2022 HP, 4.2.11 (4) (c)
NCC 2022 HP, 4.2.11 (4) (c)
NCC 2022 HP, 4.2.11 (4) (a)
NCC 2022 HP, 4.2.11 (4) (b)
NCC 2022 HP, 4.2.11 (4) (c)
- Footings and Slabs must comply with the NCC
- If Edge Beam ≥ 300mm, provide extra bottom bar for every added 100mm widthNCC 2022 HP, 4.2.14
- Reinforcement at re-entrant corners
- 45° across corner placementNCC 2022 HP, 4.2.11 (4) (c)
- Centered at internal angle of slabNCC 2022 HP, 4.2.11 (4) (c)
- ≥ 2m length of 2 strips 3-L8TM orNCC 2022 HP, 4.2.11 (4) (a)
- 1 strip 3-L11TM or 3-N12 barsNCC 2022 HP, 4.2.11 (4) (b)NCC 2022 HP, 4.2.11 (4) (c)
NCC 2022 HP, 4.2.11 (7) (e)
NCC 2022 HP, 4.2.11 (7) (a)
NCC 2022 HP, 4.2.11 (7) (d)
- ≤ 800mm CTS bar chairs spacingNCC 2022 HP, 4.2.11 (7) (e)
- Firmly fixed & supported off the groundNCC 2022 HP, 4.2.11 (7) (a)
- Wire chairs with concrete cover & placed on flat basesNCC 2022 HP, 4.2.11 (7) (d)
Concentrated Load
Localised Thickening RULES
NCC 2022 V1
All Building Classes
NCC 2022, 4.2.20
May 2023
NCC 2022 HP, 4.2.20 (b)
NCC 2022 HP, 4.2.20 (c)
NCC 2022 HP, 4.2.20 (a) (i)
NCC 2022 HP, 4.2.20 (a) (ii)
- Centre Slab Thickening beneath steel columnNCC 2022 HP, 4.2.20 (b)
- SL72 reinforcement with ≥ 50mm concrete coverNCC 2022 HP, 4.2.20 (c)
- Concentrated load (see Table for Tiled or Timber Floor & Metal Roof)NCC 2022 HP, 4.2.20 (a) (i)NCC 2022 HP, 4.2.20 (a) (ii)
NCC 2022 HP, 4.2.20 (b)
NCC 2022 HP, 4.2.20 (c)
- Centred beneath steel ColumnNCC 2022 HP, 4.2.20 (b)
- SL72 reinforcementNCC 2022 HP, 4.2.20 (c)
Concrete Slab
Concrete Slab on Ground RULES
NCC 2022 V3
Class 1 & 10a
NCC 2022 HP13.2.6 [2019: 3.12.1.5]
May 2023
NCC 2022 HP, 13.2.6 (5) (b) (ii)
NCC 2022 HP, 13.2.6 (5) (b) (i)
NCC 2022 HP, 13.2.6 (4)
NCC 2022 HP, 13.2.6 (6) (a)
NCC 2022 HP, 13.2.6 (6) (b) (i)
Under Slab
- R ≥ 2.0 in climate zone 8NCC 2022 HP, 13.2.6 (5) (b) (ii)
Slab Edges
- R ≥ 1.0 in climate zone 8NCC 2022 HP, 13.2.6 (5) (b) (i)
- R ≥ 1.0 if in floor heating or cooling system installedNCC 2022 HP, 13.2.6 (4)
Insulation
- Water-resistantNCC 2022 HP, 13.2.6 (6) (a)
- Continuous over the vertical edges or ≥ 300mm deepNCC 2022 HP, 13.2.6 (6) (b) (i)
NCC 2022 HP, 13.2.6 (5) (b) (ii)
NCC 2022 HP, 13.2.6 (5) (b) (i)
- Under Slab R ≥ 2.0NCC 2022 HP, 13.2.6 (5) (b) (ii)
- Slab Edges R ≥ 1.0NCC 2022 HP, 13.2.6 (5) (b) (i)
Termite Management
- Termite control required for Ground Level floor junctions
- ≥ 75mm slab exposure above the external finished floor level to allow easy detection of termites[1]
Termite MANAGEMENT
NCC 2022 V3
All Building Classes
NCC 2022 H1D3 & 3.4.2 [2019 3.1.4.3]
May 2023
NCC 2022 HP, 3.4.2
AS 3660.1:2014, 4.4
- Termite Management compliance to the NCC
Inspection ZoneNCC 2022 HP, 3.4.2AS 3660.1:2014, 4.4
- ≥ 75mm exposed Concrete Face
- Off form, smooth surface, free of Ripples or Honeycombing
- Tiling, Render, Vapour Barrier, Flashings, Structures & the like, not allowed to bridge this Zone
AS 3660.1:2014, 4.4
- Termite control required for Ground Level floor junctions
- ≥ 75mm slab exposure above the external finished floor level to allow easy detection of termitesAS 3660.1:2014, 4.4
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