Part 4.2 Footings, slabs and associated elements

ABCB Housing Provisions

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4.2

Part 4.2 Footings, slabs and associated elements

4.2.1

Application

New for 2022

New for 2022

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4.2.2

Site classification

2019: 3.2.4.1

The foundations where footings and slabs are to be located must be classified in accordance with AS 2870.

Explanatory information

Explanatory Table 4.2.2 provides a general description of foundation soil types that will assist in the classification of a site. More detailed information, including differentiation between classifications, can be found in AS 2870 or alternatively contact the appropriate authority.

Due to the limitations of this Part, if a site is classified H, E or P then reference must be made to AS 2870 for design and construction information.

Class	Foundation
A	Most sand and rock sites with little or no ground movement from moisture changes
S	Slightly reactive clay sites with only slight ground movement from moisture changes
M	Moderately reactive clay or silt sites which can experience moderate ground movement from moisture changes
H	Highly reactive clay sites which can experience high ground movement from moisture changes
E	Extremely reactive clay sites which can experience extreme ground movement from moisture changes
A to P	Filled sites — see AS 2870
P	Sites which include soft soils, such as soft clay or silt or loose sands; landslip; mine subsidence; collapsing soils; soils subject to erosion; reactive sites subject to abnormal moisture conditions or sites which cannot be classified otherwise.

2019: 3.2.4.1

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4.2.3

Excavation for footings

2019: 3.2.2.1

(1) Excavation for footings, including thickenings for slabs and pads must be clean cut with vertical sides, wherever possible.

(2) The base of the excavation must be—

for flat sites, generally level but may slope not more than 1:40 to allow excavations to drain; and
for sloping sites at an angle of not more than 1:10; and
for stepped footings in accordance with 4.2.7.

(3) Footing excavations must be free of loose earth, tree roots, mud or debris.

(4) Topsoil containing grass roots must be removed from the site of the foundation.

(5) Excavation depths and soil cuts must comply with Part 3.2.

(6) On loose sand sites or sites subject to wind or water erosion, the depth below finished ground level to the bottom of footings must be not less than 300 mm.

(7) The height of a finished slab-on-ground must be in accordance with 3.3.3(b).

2019: 3.2.2.1

State variations

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4.2.4

Filling under concrete slabs

2019: 3.2.2.2

Filling placed under a slab (except where the slab is suspended) must comply with the following:

Filling must be either controlled fill or rolled fill as follows:
1. Sand used in controlled fill or rolled fill must not contain any gravel size material and achieve a blow count of 7 or more per 300 mm using the test method described in AS 1289.6.3.3.
2. Clay used in controlled fill or rolled fill must be moist during compaction.
3. Controlled fill:
  1. Sand fill up to 800 mm deep — well compacted in layers not more than 300 mm deep by vibrating plate or vibrating roller.
  2. Clay fill up to 400 mm deep — well compacted in layers of not more than 150 mm by a mechanical roller.
4. Rolled fill:
  1. Sand fill up to 600 mm deep — compacted in layers of not more than 300 mm by repeated rolling by an excavator or other suitable mechanical equipment.
  2. Clay fill up to 300 mm deep — compacted in layers of not more than 150 mm by repeated rolling by an excavator or similar machine.
A level layer of clean quarry sand must be placed on top of the fill, with a depth of not less than 20 mm.
A graded stone termite management system complying with Part 3.4 may be substituted for the sand required in (b).

2019: 3.2.2.2

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4.2.5

Foundations for footings and slabs

2019: 3.2.2.3

Footings and slabs, including internal and edge beams, must be founded on soil with an allowable bearing pressure as follows:

Slab panels, load support panels and internal beams — natural soil with an allowable bearing pressure of not less than 50 kPa or controlled fill or rolled fill compacted in accordance with 4.2.4.
Edge beams connected to the slab — natural soil with an allowable bearing pressure of not less than 50 kPa or controlled fill compacted in accordance with 4.2.4(a)(iii) and extending past the perimeter of the building 1 m with a slope ratio not steeper than 2 horizontal to 1 vertical (see Figure 4.2.5).
Pad footings, strip footings and edge beams not connected to the slab, must be—
1. founded in natural soil with an allowable bearing pressure of not less than 100 kPa; or
2. for Class A and S sites they may be founded on controlled sand fill in accordance with 4.2.4(a).

Explanatory information

The foundations of a building are critical to its successful performance. As such, the soil must have the strength or bearing capacity to carry the building load with minimum movement.

The bearing capacity of a soil varies considerably and needs to be determined on a site by site basis. For this to occur, the appropriate people need to be consulted. These people may include a qualified engineer or experienced engineering geologist, or it may be determined by a person with appropriate local knowledge. The minimum bearing capacity (soil strength rating) may depend on the site conditions. The soil may be naturally undisturbed or be disturbed by building work or the like. Where soil is disturbed by building work and the like, the bearing capacity can be dramatically altered. This is typically the case for sloping sites where cut and fill procedures are used. In these situations the soil needs to be consolidated, generally via compaction, to achieve the required bearing capacity.

There are a number of alternatives for working on cut and filled sites. These are described in Figure 4.2.5.

Option 1 of Figure 4.2.5 refers to the controlled fill process which involves the compaction of fill in layers to achieve the bearing capacity described in 4.2.5. The depth of fill for each layer is specified to ensure effective compaction. Fill beyond these depths will need to be installed in accordance with H1D4(1).

Option 2 and 3 of Figure 4.2.5 refer to edge beams that extend through the fill into undisturbed soil which provides the 4.2.5 required bearing capacity. In this situation the fill is essentially only taking the internal slab loads.

2019: 3.2.2.3

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4.2.6

Slab edge support on sloping sites

2019: 3.2.2.4

Footings and slabs installed on the low side of sloping sites must be as follows:

Slab panels — in accordance with 4.2.5(a).
Edge beams—
1. supported by controlled fill in accordance with 4.2.5(b) (see Figure 4.2.5, Option 1); or
2. supported by deepened edge beams or bulk piers designed in accordance with AS 3600 (see Figure 4.2.5, Option 2); or
3. deepened (as per AS 2870) to extend into the natural soil level with a bearing capacity in accordance with 4.2.5(b) (see Figure 4.2.5, Option 3); or
4. stepped in accordance with AS 2870.
Edge beams not connected to the slab, pad footings and strip footings — founded in accordance with 4.2.5(c).
Where an excavation (cut) of the natural ground is used it must be in accordance with Part 3.2.

2019: 3.2.2.4

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4.2.7

Stepped footings

2019: 3.2.2.5

2019: 3.2.2.5

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4.2.8

Vapour barriers

2019: 3.2.2.6

NCC Blurbs

(1) A damp-proofing membrane must be installed under slab-on-ground construction for a Class 1 building and for a Class 10 building where the slab is continuous with the slab of a Class 1 building in accordance with (2), (3), (4) and (5).

(2) Materials: A damp-proofing membrane must be—

0.2 mm nominal thickness polyethylene film; and
high impact resistant,

determined in accordance with criteria specified in clause 5.3.3.3 of AS 2870.

(3) A damp-proofing membrane must be branded continuously “AS 2870 Concrete underlay, 0.2 mm High impact resistance”.

(4) Installation: A damp-proofing membrane must be installed as follows—

Lap not less than 200 mm at all joints.
Tape or seal with a close-fitting sleeve around all service penetrations.
Fully seal where punctured (unless for service penetrations) with additional polyethylene film and tape.

(5) The damp-proofing membrane must be placed beneath the slab so that the bottom surface of the slab is entirely underlaid and must extend under internal and edge beams to finish at ground level in accordance with Figure 4.2.8.

Notes

A range of polyethylene films can be used, including black film and orange film, provided they satisfy the requirements for high impact resistance in accordance with the criteria specified in clause 5.3.3.3 of AS 2870.

NCC Title

Damp-proofing membrane

NCC State

NSW

NCC Variation Type

Replacement

NCC SPTC Current

Damp-proofing membrane

(1) A vapour barrier must be installed under slab-on-ground construction for a Class 1 building and for a Class 10 building where the slab is continuous with the slab of a Class 1 building in accordance with (2), (3), (4) and (5).

(2) Materials: A vapour barrier must be—

0.2 mm nominal thickness polyethylene film; and
medium impact resistant,

determined in accordance with criteria specified in clause 5.3.3.3 of AS 2870.

(3) A vapour barrier must be branded continuously “AS 2870 Concrete underlay, 0.2 mm Medium impact resistance”.

(4) Installation: A vapour barrier must be installed as follows:

Lap not less than 200 mm at all joints.
Tape or seal with a close-fitting sleeve around all service penetrations.
Fully seal where punctured (unless for service penetrations) with additional polyethylene film and tape.

(5) The vapour barrier must be placed beneath the slab so that the bottom surface of the slab is entirely underlaid and must extend under internal and edge beams to finish at ground level in accordance with Figure 4.2.8.

2019: 3.2.2.6

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4.2.9

Edge rebates

2019: 3.2.2.7

Edge rebates for slab-on-ground and stiffened raft with masonry cavity or veneer construction must comply with the following:

The rebate must not be less than 20 mm.
The edge rebate must be flashed and drained in accordance with H2D4 and where it cannot be flashed, it must be filled with mortar.

Explanatory information

See 4.2.21 for minimum edge beam details. For single skin or framed walls with external cladding, rebates are not required.

2019: 3.2.2.7

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4.2.10

Concrete

2019: 3.2.3.1

NCC Blurbs

Concrete must comply with the following:

Concrete must be manufactured to comply with AS 3600; and—
1. have a strength at 28 days of not less than 20 MPa (denoted as N20 grade); and
2. have a 20 mm maximum nominal aggregate size; and
3. have a nominal 100 mm slump.
Water must not be added to the mix to increase the slump to a value in excess of that specified.
Concrete must be placed, compacted and cured in accordance with good building practice.
Concrete in slabs must be adequately compacted, and slab surfaces, including edges, moist cured for 7 days.
After vertical surfaces are stripped of formwork, slab edges must be finished prior to curing.
Loading of concrete slabs with stacked materials or building plant must not occur for a minimum of 7 days after pouring although construction of wall frames and setting out brickwork may be undertaken during this period.
Concrete must not be poured if the air temperature on site exceeds 32ºC unless written instructions from a Professional Engineer are followed.

Explanatory information

Complete discharge of the concrete from the truck should be made within one and a half hours of initial mixing with water unless a suitable retarder has been specified.
Compacting concrete by vibration removes air pockets and works the concrete thoroughly around reinforcement, service penetrations etc. and into corners of formwork to increase durability and resistance to termite infestation and salt damp attack. Care should be taken not to over-vibrate. The finishing and curing of slab edges provides an improved edge finish which is resistant to edge dampness.
Care should be taken when using chemical curing methods, because some products may not be compatible with adhesives used to fix surface finishes to the slab.

NCC Title

Concrete

NCC State

NCC Variation Type

Replacement

NCC SPTC Current

Concrete

Concrete must comply with the following:

Concrete must comply with AS 3600; and—
1. have a strength at 28 days of not less than 20 MPa (denoted as N20 grade); and
2. have a 20 mm maximum nominal aggregate size; and
3. have a nominal 100 mm slump.
Water must not be added to the mix to increase the slump to a value in excess of that specified.
Concrete must be placed, compacted and cured in accordance with good building practice.

Explanatory information

Complete discharge of the concrete from the truck should be made within one and a half hours of initial mixing with water unless a suitable retarder has been specified.
Compacting concrete by vibration removes air pockets and works the concrete thoroughly around reinforcement, service penetrations etc. and into corners of formwork to increase durability and resistance to termite infestation and salt damp attack. Care should be taken not to over-vibrate. The finishing and curing of slab edges provides an improved edge finish which is resistant to edge dampness.
Care should be taken when using chemical curing methods, because some products may not be compatible with adhesives used to fix surface finishes to the slab.

2019: 3.2.3.1

State variations

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4.2.11

Steel reinforcement

2019: 3.2.3.2

(1) Materials used for reinforcing steel must comply with AS 2870 and be—

welded wire reinforcing fabric; or
trench mesh; or
steel reinforcing bars.

(2) Steel reinforcing bars may be substituted for trench mesh in accordance with Table 4.2.11a.

(3) Minimum laps for reinforcement as shown in Table 4.2.11b and Figure 4.2.11a must be provided where reinforcing is used.

(4) Any slab in H1D4 with a re-entrant corner must have—

two strips of 3-L8TM; or
one strip of 3-L11TM; or
3-N12 bars,

not less than 2 m in length and placed at an angle of 45° across the corner such that the centre of the 2 m length is at the location of the internal angle of the slab in accordance with Figure 4.2.11b.

(5) Footings and slabs-on-ground must have concrete cover between the outermost edge of the reinforcement (including ligatures, tie wire etc.) and the surface of the concrete of not less than—

40 mm to unprotected ground; and
30 mm to a membrane in contact with the ground; and
20 mm to an internal surface; and
40 mm to external exposure.

(6) Reinforcement must be free of loose rust, mud, paints and oils.

(7) Reinforcement must be placed as follows:

All reinforcement must be firmly fixed in place to prevent it moving during concreting operations.
Reinforcement must be supported off the ground or the forms by bar chairs made from wire, concrete or plastic.
When using wire chairs, the minimum concrete cover (see (5)) to the uncoated portion of the chair must be obtained.
Wire chairs on soft ground or plastic membrane must be placed on flat bases.
Bar chairs must be spaced at not more than 800 mm centres for steel fabric.

Trench mesh (TM)	Area — mm²	Reinforcing bar alternative	Trench mesh alternative
2-L8TM	91	2-N10 or 1-N12	Not applicable
3-L8TM	136	2-N10 or 2-N12	Not applicable
4-L8TM	182	2-N12	2-L11TM
5-L8TM	227	2-N12	3-L11TM
2-L11TM	180	1-N16 or 2-N12	2x2-L8TM
3-L11TM	270	3-N12	2x3-L8TM
4-L11TM	360	2-N16	2x4-L8TM
2-L12TM	222	2-N12	3-L11TM
3-L12TM	333	3-N12	4-L11TM
4-L12TM	444	4-N12	5-L11TM

Reinforcement	Minimum splice	Minimum lap at “T” intersections	Minimum lap at “L” intersections
Steel reinforcing bars ≤12 mm diameter	500 mm	Full width across the junction	One outer bar must be bent and continue 500 mm (min) around corner
Steel reinforcing bars >12 mm to ≤16 mm diameter	700 mm	Full width across the junction	One outer bar must be bent and continue 500 mm (min) around corner
Trench mesh	500 mm	Full width across the junction	Full width across the junction
Square and rectangular mesh	The two outermost transverse wires of one sheet must overlap the two outermost transverse wires of the other	Not applicable	Not applicable

Explanatory information: Reinforcement types

Reinforcement types referenced in this clause are described as follows:

Square mesh is designated in terms of the diameter of each bar and the spacing of consecutive bars. For example, SL62 consists of 6 mm bar at 200 mm spacings.
Trench mesh is designated in terms of the number of longitudinal bars and the diameter of each bar. For example, 3-L11TM consists of 3 longitudinal bars each of which are 11 mm in diameter.
Reinforcing bars are designated in terms of the number of bars and the diameter of each bar. For example, 6-N12 consists of 6 bars each of which are 12 mm in diameter.

Explanatory information: Cleaning and placement of reinforcing

In order to obtain a good bond between concrete and reinforcement, the reinforcement should be free of contamination by mud, paint, oils, etc. It is not necessary for the reinforcement to be completely free of rust. Some rusting is beneficial in promoting a good bond as it roughens the surface of the steel. Loose rust, however, must be removed from the reinforcement.

Reinforcement is designed to be in a particular place so as to add strength or to control cracking of the concrete. A displacement from its intended location could make a significant difference to the life or serviceability of the structure.

Supports for fabric reinforcement are provided to prevent the fabric distorting when workers walk on top of it to place the concrete and maintain the correct concrete cover to the fabric.

2019: 3.2.3.2

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4.2.12

Footing and slab construction

2019: 3.2.5.1

Footing and slab construction, including size and placement of reinforcement, must be in accordance with the relevant provisions of—

4.2.13 for footings for stumps; and
4.2.14 for stiffened rafts on Class A, S and M sites; and
4.2.15 for strip footing systems on Class A, S and M sites; and
4.2.16 for footing slabs on Class A sites; and
4.2.17 for footings for single leaf masonry, mixed construction and earth retaining walls; and
4.2.18 for footings for fireplaces on Class A and S sites; and
4.2.19 for shrinkage control; and
4.2.20 for concentrated loads; and
4.2.21 for minimum edge beam dimensions; and
4.2.22 for recessed areas of slabs.

2019: 3.2.5.1

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4.2.13

Stump footing details

2019: 3.2.5.6

(1) Footings for stumps must comply with—

the provisions of Tables 4.2.13a, 4.2.13b or 4.2.13c for Class A and Class S sites; or
the appropriate referenced document listed in—
1. H1D6(3); or
2. H1D4.

(2) Concrete stumps must—

be designed in accordance with—
1. AS 3600; or
2. Tables 4.2.13d, 4.2.13e or 4.2.13f; and
use a minimum 20 MPa concrete as defined in AS 3600.

(3) Steel stumps must be—

designed in accordance with—
1. AS 4100; or
2. Tables 4.2.13d, 4.2.13e or 4.2.13f; and
fully enclosed and sealed with a welded top plate; and
encased in concrete sloping away from the stump and finishing not less than 100 mm above finished ground level; and
corrosion protected in accordance with Part 6.3.

(4) Timber stumps must be designed in accordance with—

AS 1684.2, AS 1684.3, AS 1684.4 or AS 1720.1; or
Tables 4.2.13d, 4.2.13e or 4.2.13f.

(5) Stumps must be braced—

by a full perimeter masonry base; or
for concrete stumps — in accordance with AS 3600; or
for steel stumps — in accordance with AS 4100; or
for timber stumps — in accordance with AS 1684.2, AS 1684.3, AS 1684.4 or AS 1720.1.

(6) Stumps must be embedded into the foundation material not less than 30% of their height above ground level or 450 mm, whichever is the greater.

(7) Pad footings for clad frame, Class A and Class S sites, must be in accordance with Table 4.2.13g and Figure 4.2.13.

Floor load area (m²)	Dimension (mm)	Roof load area (m²)
3	Square pad footing size	250 x 250	300 x 300	350 x 350
8	Square pad footing size	400 x 400	400 x 400	450 x 450
12	Square pad footing size	450 x 450	500 x 500	500 x 500
3	Circular pad footing diameter	300	400	400
8	Circular pad footing diameter	450	450	600
12	Circular pad footing diameter	600	600	600
3	Pad footing depth	250	250	250
8	Pad footing depth	250	250	250
12	Pad footing depth	250	250	250

Floor load area (m²)	Dimension (mm)	Roof load area (m²)
3	Square pad footing size	300 x 300	400 x 400	450 x 450
8	Square pad footing size	450 x 450	500 x 500	550 x 500
12	Square pad footing size	500 x 500	550 x 550	600 x 600
3	Circular pad footing diameter	400	450	600
8	Circular pad footing diameter	600	600	650
12	Circular pad footing diameter	650	650	700
3	Pad footing depth	250	250	250
8	Pad footing depth	250	250	250
12	Pad footing depth	250	300	300

Floor load area (m²)	Dimension (mm)	Roof load area (m²)
3	Square pad footing size	350 x 350	400 x 400	450 x 450
8	Square pad footing size	550 x 550	550 x 550	600 x 600
12	Square pad footing size	650 x 650	650 x 650	700 x 700
3	Circular pad footing diameter	400	450	600
8	Circular pad footing diameter	650	650	700
12	Circular pad footing diameter	750	750	800
3	Pad footing depth	250	250	250
8	Pad footing depth	300	300	350
12	Pad footing depth	350	350	350

Table 4.2.13d Maximum stump height (mm): stump supporting single storey timber floor and metal roof

Stump material	Section size (mm)	Floor load area (m²)	Roof load area (m²)
Stump material	Section size (mm)	Floor load area (m²)	0	6	12
Concrete f’_c= 20 MPa	100 x 100	3	2500	2000	1750
Concrete f’_c = 20 MPa	100 x 100	8	1500	1500	1500
Concrete f’_c = 20 MPa	100 x 100	12	1250	1250	1250
Steel f_y = 350 MPa	100 x 100 x 2.0	3	3000	3000	3000
Steel f_y = 350 MPa	100 x 100 x 2.0	8	3000	3000	3000
Steel f_y = 350 MPa	100 x 100 x 2.0	12	3000	3000	3000
Timber F17	100 x 100	3	3000	3000	3000
Timber F17	100 x 100	8	2500	2500	2250
Timber F17	100 x 100	12	2250	2000	2000
Timber F14	100 x 100	3	3000	3000	2500
Timber F14	100 x 100	8	2250	2000	1750
Timber F14	100 x 100	12	1750	1500	1500
Timber F11	100 x 100	3	3000	2500	2250
Timber F11	100 x 100	8	2000	1750	1750
Timber F11	100 x 100	12	1500	1500	1250
Timber F8	100 x 100	3	3000	2500	2000
Timber F8	100 x 100	8	1750	1500	1250
Timber F8	100 x 100	12	1250	1000	750
Timber F7	100 x 100	3	2500	2250	1750
Timber F7	100 x 100	8	1500	1250	750
Timber F7	100 x 100	12	750	–	–
Timber F5	100 x 100	3	2500	2000	1500
Timber F5	100 x 100	8	1250	750	–
Timber F5	100 x 100	12	–	–	–

Table Notes

Load accounted for includes 0.53 kPa permanent floor, 0.92 kN/m permanent wall, 0.4 kPa permanent roof, permanent member self-weight, 1.5 kPa or 1.1 kN imposed floor and 0.25 kPa imposed roof.
Load combinations for ULS included are 1.35G and 1.2G + 1.5Q for stumps and G + 0.5Q for pad footings.
Minimum bearing pressure is 100 kPa for pad footings.
Stumps are assumed to be braced and simply-supported at both ends with an effective length factor of 1.
A maximum load eccentricity of length/100 has been accounted for in the stumps.
A roof load area of “0” must be used for stumps not supporting roof loads.
The length of wall load allowed for is equal to the square root of the floor area.

Table 4.2.13e Maximum stump height: stump supporting single storey tiled floor and tiled roof

Stump material	Section size (mm)	Floor load area (m²)	Roof load area (m²)
Stump material	Section size (mm)	Floor load area (m²)	0	6	12
Concrete f’_c = 20 MPa	100 x 100	3	2250	1750	1500
Concrete f’_c = 20 MPa	100 x 100	8	1500	1250	1250
Concrete f’_c = 20 MPa	100 x 100	12	1250	1250	750
Steel f_y = 350 MPa	100 x 100 x 2.0	3	3000	3000	3000
Steel f_y = 350 MPa	100 x 100 x 2.0	8	3000	3000	3000
Steel f_y = 350 MPa	100 x 100 x 2.0	12	3000	3000	3000
Timber F17	100 x 100	3	3000	3000	2500
Timber F17	100 x 100	8	2500	2250	2000
Timber F17	100 x 100	12	2000	2000	1750
Timber F14	100 x 100	3	3000	2500	2000
Timber F14	100 x 100	8	2000	1750	1500
Timber F14	100 x 100	12	1500	1250	1000
Timber F11	100 x 100	3	3000	2250	2000
Timber F11	100 x 100	8	1750	1500	1250
Timber F11	100 x 100	12	1250	1000	750
Timber F8	100 x 100	3	2500	2000	1750
Timber F8	100 x 100	8	1500	1250	1000
Timber F8	100 x 100	12	1000	500	–
Timber F7	100 x 100	3	2500	1750	1250
Timber F7	100 x 100	8	1250	750	–
Timber F7	100 x 100	12	–	–	–
Timber F5	100 x 100	3	2250	1500	1000
Timber F5	100 x 100	8	750	–	–
Timber F5	100 x 100	12	–	–	–

Table Notes

Load accounted for includes 0.98 kPa permanent floor, 0.92 kN/m permanent wall, 0.85 kPa permanent roof, permanent member self-weight, 1.5 kPa or 1.1 kN imposed floor and 0.25 kPa imposed roof.
Load combinations for ULS included are 1.35G and 1.2G + 1.5Q for stumps and G + 0.5Q for pad footings.
Minimum bearing pressure is 100 kPa for pad footings.
Stumps are assumed to be braced and simply-supported at both ends with an effective length factor of 1.
A maximum load eccentricity of length/100 has been accounted for in the stumps.
A roof load area of “0” must be used for stumps not supporting roof loads.
The length of wall load allowed for is equal to the square root of the floor area.

Table 4.2.13f Maximum stump height: stump supporting double storey timber floor and metal roof

Stump material	Section size (mm)	Floor load area (m²)	Roof load area (m²)
Stump material	Section size (mm)	Floor load area (m²)	0	6	12
Concrete f’_c = 20 MPa	100 x 100	3	1750	1500	1500
Concrete f’_c = 20 MPa	100 x 100	8	1250	1000	750
Concrete f’_c = 20 MPa	100 x 100	12	–	–	–
Steel f_y = 350 MPa	100 x 100 x 2.0	3	3000	3000	3000
Steel f_y = 350 MPa	100 x 100 x 2.0	8	3000	3000	3000
Steel f_y = 350 MPa	100 x 100 x 2.0	12	3000	2750	2500
Timber F17	100 x 100	3	3000	2500	2500
Timber F17	100 x 100	8	1750	1750	1500
Timber F17	100 x 100	12	1250	1250	1250
Timber F14	100 x 100	3	2500	2250	2000
Timber F14	100 x 100	8	1250	1250	1000
Timber F14	100 x 100	12	750	500	500
Timber F11	100 x 100	3	2250	2000	1750
Timber F11	100 x 100	8	1000	1000	750
Timber F11	100 x 100	12	–	–	–
Timber F8	100 x 100	3	2000	1750	1500
Timber F8	100 x 100	8	500	500	–
Timber F8	100 x 100	12	–	–	–
Timber F7	100 x 100	3	1750	1500	1250
Timber F7	100 x 100	8	–	–	–
Timber F7	100 x 100	12	–	–	–
Timber F5	100 x 100	3	1500	1000	750
Timber F5	100 x 100	8	–	–	–
Timber F5	100 x 100	12	–	–	–

Table Notes

Load accounted for includes 0.53 kPa permanent floor, 0.92 kN/m permanent wall, 0.4 kPa permanent roof, permanent member self-weight, 1.5 kPa or 1.1 kN imposed floor and 0.25 kPa imposed roof.
Load combinations for ULS included are 1.35G and 1.2G + 1.5Q for stumps and G + 0.5Q for pad footings.
Minimum bearing pressure is 100 kPa for pad footings.
Stumps are assumed to be braced and simply-supported at both ends with an effective length factor of 1.
A maximum load eccentricity of length/100 has been accounted for in the stumps.
A roof load area of “0” must be used for stumps not supporting roof loads.
The length of wall load allowed for is equal to the square root of the floor area.

Effective supported areas (m²)	Width of square pad (mm)	Width of circular pad (mm)	Thickness (t) (mm)	Depth (mm)
10	400	500	200	400
20	500	600	200	400
30	600	750	250	400

2019: 3.2.5.6

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4.2.14

Stiffened rafts Class A, S and M sites

New for 2022

Footing and stiffened raft slabs must comply with—

For Class A and S sites — Tables 4.2.14a, 4.2.14b and Figure 4.2.14a; and
For Class M sites — Table 4.2.14c and Figure 4.2.14b.

Type of construction	Depth (D) (mm)	Bottom reinf.	Max. spacing c/l to c/l	Slab fabric
Clad frame	300	3-L8TM	N/A	SL72
Articulated masonry veneer	300	3-L8TM	N/A	SL72
Masonry veneer	300	3-L8TM	N/A	SL72
Articulated full masonry	400	3-L8TM	N/A	SL72
Full masonry	400	3-L8TM	N/A	SL72

Type of construction	Depth (D) (mm)	Bottom reinf.	Max. spacing c/l to c/l	Slab fabric
Clad frame	300	3-L8TM	N/A	SL72
Articulated masonry veneer	300	3-L8TM	N/A	SL72
Masonry veneer	300	3-L11TM	N/A	SL72
Articulated full masonry	450	3-L11TM	N/A	SL72
Full masonry	450	3-N16	5.0 (m) ^{Note 2}	SL82

Type of construction	Depth (D) (mm)	Bottom reinf.	Max. spacing c/l to c/l	Slab mesh
Clad frame	300	3-L11TM	6.0^{Note 2}	SL72
Articulated masonry veneer	400	3-L11TM	6.0^{Note 2}	SL72
Masonry veneer	400	3-L11TM	5.0^{Note 2}	SL72
Articulated full masonry	500	3-L12TM	4.0	SL82
Full masonry	850	3-N16	4.0	SL92

New for 2022

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4.2.15

Strip footings Class A, S and M sites

New for 2022

Strip footings for Class A, S and M sites must comply with—

for Class A and S sites — Tables 4.2.15a, 4.2.15b and Figure 4.2.15a; and
for Class M sites — Table 4.2.15c and Figure 4.2.15b.

Type of construction	D (mm)	B (mm)	Reinforcement (top and bottom)
Clad frame	300	300	3–L8TM
Articulated masonry veneer	300	300	3–L8TM
Masonry veneer	300	300	3–L8TM
Articulated full masonry	300	400	4–L8TM
Full masonry	300	400	4–L8TM

Type of construction	D (mm)	B (mm)	Reinforcement (top and bottom)
Clad frame	400	300	3–L8TM
Articulated masonry veneer	400	300	3–L8TM
Masonry veneer	400	300	3–L8TM
Articulated full masonry	400	400	4–L11TM
Full masonry	500	400	4–L11TM

Type of construction	D (mm)	B (mm)	Reinforcement (top and bottom)
Clad frame	400	300	3-L11TM
Articulated masonry veneer	450	300	3-L11TM
Masonry veneer	500	300	3-L12TM
Articulated full masonry	600	400	4-L12TM
Full masonry	900 ^{Note 2}	400	4-L12TM

New for 2022

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4.2.16

Footing slabs for Class A sites

New for 2022

Footing slabs for Class A sites supporting the following external wall types must comply with Figure 4.2.16:

Clad frame.
Articulated masonry.
Masonry veneer.
Articulated full masonry.
Full masonry.

New for 2022

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4.2.17

Footings for single leaf masonry, mixed construction and earth wall construction

2019: 3.2.5.2

Footings supporting the following external wall types must comply with the equivalent wall construction set out in Tables 4.2.17a, 4.2.17b and 4.2.17c:

Single leaf masonry.
Mixed construction.
Earth wall structures.

Actual construction: external walls	Actual construction: internal walls	Equivalent wall construction
Reinforced single leaf masonry	Articulated masonry on Class A and Class S sites, or framed	Articulated masonry veneer
Reinforced single leaf masonry	Articulated masonry or reinforced single leaf masonry	Masonry veneer
Articulated single leaf masonry	Articulated masonry	Articulated full masonry

Actual construction: external walls	Actual construction: internal walls	Equivalent wall construction
Full masonry	Framed	Articulated full masonry
Articulated full masonry	Framed	Masonry veneer

Actual construction: external walls	Actual construction: internal walls	Equivalent wall construction
Infill panels of earth wall construction	Framed earth wall construction	Articulated masonry veneer
Loadbearing earth wall construction	Loadbearing earth wall construction	Articulated full masonry

Explanatory information

Tables 4.2.17a, 4.2.17b and 4.2.17c provide solutions for footings that are equivalent to those supporting a wall type that may be different to the actual type included in design documentation. The equivalent wall construction in the right-hand column of each of these tables recognises the types of footing systems suitable to support the actual external wall and internal wall types that may not have a specific solution for supporting footings.

2019: 3.2.5.2

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4.2.18

Footings for fireplaces on Class A and S sites

2019: 3.2.5.5

(1) Fireplaces on Class A and S sites must be supported on a pad footing—

150 mm thick for single storey (one trafficable floor and a wall height not more than 4.2 m) construction; and
200 mm thick for 2 storey (two trafficable floors and a wall height not more than 8 m) construction; and
reinforced top and bottom with SL72 mesh; and
extending 300 mm past the edges of the masonry except for any edge flush with the outer wall.

(2) The pad footing must form an integral part of the slab.

2019: 3.2.5.5

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4.2.19

Shrinkage control

2019: 3.2.5.3

Where brittle floor coverings, such as ceramic tiles, are to be used over an area greater than 16 m², one of the following additional measures must be taken to control the effect of shrinkage cracking—

the amount of shrinkage reinforcement (steel reinforcement mesh in the slab panel) must be—
1. increased to SL92 or equivalent throughout the affected slab area; or
2. reinforced top and bottom with sheets of slab mesh throughout the affected slab area; or
the bedding system for brittle coverings must be selected on the basis of the expected slab movement and the characteristics of the floor covering (including the use of expansion joints etc.); or
the placement of floor covering must be delayed for not less than 3 months after the concrete has been poured.

2019: 3.2.5.3

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4.2.20

Concentrated loads

New for 2022

Where a footing or slab supports a concentrated load from a structural steel column, localised thickening must—

be provided in accordance with—
1. for tiled floor and tiled roof, Tables 4.2.20a, 4.2.20b or 4.2.20c; or
2. for timber floor and metal roof, Tables 4.2.20d, 4.2.20e or 4.2.20f; and
be centred under the structural steel column; and
have SL72 reinforcement with a minimum 50 mm of concrete cover (see Figure 4.2.20).

Localised thickening	Maximum floor load area (m²)
Square thickening size (mm)	450 x 450	650 x 650	850 x 850
Thickening depth (mm)	250	350	400

Localised thickening	Maximum floor load area (m²)
Square thickening size (mm)	650 x 650	800 x 800	950 x 950
Thickening depth (mm)	350	400	450

Localised thickening	Maximum floor load area (m²)
Square thickening size (mm)	750 x 750	900 x 900	1000 x 1000
Thickening depth (mm)	400	450	500

Localised thickening	Maximum floor load area (m²)
Square thickening size (mm)	400 x 400	600 x 600	750 x 750
Thickening depth (mm)	250	300	350

Localised thickening	Maximum floor load area (m²)
Square thickening size (mm)	500 x 500	700 x 700	800 x 800
Thickening depth (mm)	300	350	400

Localised thickening	Maximum floor load area (m²)
Square thickening size (mm)	600 x 600	750 x 750	850 x 850
Thickening depth (mm)	300	400	450

New for 2022

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4.2.21

Minimum edge beam dimensions

2019: 3.2.5.4

2019: 3.2.5.4

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4.2.22

Recessed areas of slabs

New for 2022

(1) Where a recess in a slab is provided, it must comply with one of the following:

For recess depths less than or equal to half the nominal slab thickness, the reinforcing mesh must have a minimum lap length of 400 mm measured from the inside face of the recess (see Figure 4.2.22a).
For recess depths greater than half the nominal slab thickness (see Figure 4.2.22b)—
1. top reinforcing mesh must overlap the bottom reinforcing mesh by not less than 400 mm; and
2. bottom reinforcing mesh must be two layers of SL72.

(2) Concrete cover to reinforcing in (1)(a) and (b) must comply with 4.2.11(5).

New for 2022

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Part 4.2 Footings, slabs and associated elements

4.2.1 Application New for 2022

State variations

4.2.2 Site classification 2019: 3.2.4.1

State variations

4.2.3 Excavation for footings 2019: 3.2.2.1

State variations

4.2.4 Filling under concrete slabs 2019: 3.2.2.2

State variations

4.2.5 Foundations for footings and slabs 2019: 3.2.2.3

State variations

4.2.6 Slab edge support on sloping sites 2019: 3.2.2.4

State variations

4.2.7 Stepped footings 2019: 3.2.2.5

State variations

4.2.8 Vapour barriers 2019: 3.2.2.6

State variations

4.2.9 Edge rebates 2019: 3.2.2.7

State variations

4.2.10 Concrete 2019: 3.2.3.1

State variations

4.2.11 Steel reinforcement 2019: 3.2.3.2

State variations

4.2.12 Footing and slab construction 2019: 3.2.5.1

State variations

4.2.13 Stump footing details 2019: 3.2.5.6

State variations

4.2.14 Stiffened rafts Class A, S and M sites New for 2022

State variations

4.2.15 Strip footings Class A, S and M sites New for 2022

State variations

4.2.16 Footing slabs for Class A sites New for 2022

State variations

4.2.17 Footings for single leaf masonry, mixed construction and earth wall construction 2019: 3.2.5.2

State variations

4.2.18 Footings for fireplaces on Class A and S sites 2019: 3.2.5.5

State variations

4.2.19 Shrinkage control 2019: 3.2.5.3

State variations

4.2.20 Concentrated loads New for 2022

State variations

4.2.21 Minimum edge beam dimensions 2019: 3.2.5.4

State variations

4.2.22 Recessed areas of slabs New for 2022

State variations

4.2.1

Application

New for 2022

4.2.2

Site classification

2019: 3.2.4.1

4.2.3

Excavation for footings

2019: 3.2.2.1

4.2.4

Filling under concrete slabs

2019: 3.2.2.2

4.2.5

Foundations for footings and slabs

2019: 3.2.2.3

4.2.6

Slab edge support on sloping sites

2019: 3.2.2.4

4.2.7

Stepped footings

2019: 3.2.2.5

4.2.8

Vapour barriers

2019: 3.2.2.6

4.2.9

Edge rebates

2019: 3.2.2.7

4.2.10

Concrete

2019: 3.2.3.1

4.2.11

Steel reinforcement

2019: 3.2.3.2

4.2.12

Footing and slab construction

2019: 3.2.5.1

4.2.13

Stump footing details

2019: 3.2.5.6

4.2.14

Stiffened rafts Class A, S and M sites

New for 2022

4.2.15

Strip footings Class A, S and M sites

New for 2022

4.2.16

Footing slabs for Class A sites

New for 2022

4.2.17

Footings for single leaf masonry, mixed construction and earth wall construction

2019: 3.2.5.2

4.2.18

Footings for fireplaces on Class A and S sites

2019: 3.2.5.5

4.2.19

Shrinkage control

2019: 3.2.5.3

4.2.20

Concentrated loads

New for 2022

4.2.21

Minimum edge beam dimensions

2019: 3.2.5.4

4.2.22

Recessed areas of slabs

New for 2022