ABCB Housing Provisions
Classification
Building class 1a Building class 1b Building class 2 Building class 3 Building class 4 Building class 5 Building class 6 Building class 7a Building class 7b Building class 8 Building class 9a Building class 9b Building class 9c Building class 10a Building class 10b Building class 10c

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Classification
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4.2

Part 4.2 Footings, slabs and associated elements

Part 4.2 Footings, slabs and associated elements

Part 4.2 is subject to the limitations set out in H1D4(2).

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.

Table 4.2.2 (explanatory) General definition of site classes
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.
Table Notes
  1. For Class M, further division based on the depth of expected movement is required.
  2. For deep-seated movement, characteristic of dry climates and corresponding to a design depth of suction change HS, equal to or greater than 3 m, the classification must be M-D.
  3. If classification M-D is established due to further division, design of footings and slabs is beyond the scope of the ABCB Housing Provisions and reference must be made to AS 2870 for design and construction information.
NCC Blurbs

(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—

  1. for flat sites, generally level but may slope not more than 1:40 to allow excavations to drain; and
  2. for sloping sites at an angle of not more than 1:10; and
  3. 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) 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.

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

Notes

In New South Wales requirements for shoring and adequacy of excavation works are a prescribed condition of development consent. In addition consent authorities can place specific controls on siteworks associated with the construction of a building, by imposing further conditions of development consent.

NCC Title

Excavation for footings

NCC State
NSW
NCC Variation Type
Replacement
NCC SPTC Current
Excavation for footings

(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—

  1. for flat sites, generally level but may slope not more than 1:40 to allow excavations to drain; and
  2. for sloping sites at an angle of not more than 1:10; and
  3. 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).

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

  1. 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.
  2. A level layer of clean quarry sand must be placed on top of the fill, with a depth of not less than 20 mm.
  3. A graded stone termite management system complying with Part 3.4 may be substituted for the sand required in (b).

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

  1. 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.
  2. 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).
  3. 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).
Figure 4.2.5 Foundations for footings and slabs
image-4-2-5-foundations-for-footings-and-slabs.svg
Figure Notes

Compacted fill must be in accordance with 4.2.4.

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.

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

  1. Slab panels — in accordance with 4.2.5(a).
  2. 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.
  3. Edge beams not connected to the slab, pad footings and strip footings — founded in accordance with 4.2.5(c).
  4. Where an excavation (cut) of the natural ground is used it must be in accordance with Part 3.2.

Stepped strip footings must—

  1. have a base that is horizontal or be sloped at not more than 1:10; or
  2. be stepped in accordance with one of the methods shown in Figure 4.2.7.
Figure 4.2.7 Stepped strip footings
image-4-2-7-stepped-strip-footings.svg
Figure Notes

All dimensions in millimetres.

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—

  1. 0.2 mm nominal thickness polyethylene film; and
  2. 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—

  1. Lap not less than 200 mm at all joints.
  2. Tape or seal with a close-fitting sleeve around all service penetrations.
  3. 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
NCC Blurbs

A continuous damp-proofing membrane must be installed under slab-on-ground construction for all Class 1 buildings and for Class 10 buildings where the slab is continuous with the slab of a Class 1 building as follows—

  1. Materials: A damp-proofing membrane must be—
    1. 0.2 mm nominal thickness polyethylene film; and
    2. high impact resistant with resistance to puncturing and moisture penetration, determined in accordance with criteria specified in clause 5.3.3.3 of AS 2870; and
    3. branded continuously “AS 2870 Concrete underlay, 0.2 mm High impact resistance” together with the manufacturer’s or distributor’s name, trade mark or code.
  2. Installation: A damp-proofing membrane must be installed as follows—
    1. lap not less than 200 mm at all joints; and
    2. tape or seal with a close fitting sleeve around all service penetrations; and
    3. fully seal where punctured (unless for service penetrations) with additional polyethylene film and tape.
  3. The damp-proofing membrane must be placed beneath the slab so that the bottom surface of the slab is entirely underlaid and extends under edge beams to finish at ground level in accordance with Figure 4.2.8.
NCC Title

Damp-proofing membrane

NCC State
SA
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—

  1. 0.2 mm nominal thickness polyethylene film; and
  2. 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:

  1. Lap not less than 200 mm at all joints.
  2. Tape or seal with a close-fitting sleeve around all service penetrations.
  3. 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.

Figure 4.2.8 Acceptable vapour barrier and damp-proofing membrane location
image-4-2-8-acceptable-vapour-barrier-and-damp-proofing-membrane-location.svg
Figure Notes

All dimensions in millimetres.

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

  1. The rebate must not be less than 20 mm.
  2. 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.

NCC Blurbs

Concrete must comply with the following:

  1. 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.
  2. Water must not be added to the mix to increase the slump to a value in excess of that specified.
  3. Concrete must be placed, compacted and cured in accordance with good building practice.
  4. Concrete in slabs must be adequately compacted, and slab surfaces, including edges, moist cured for 7 days.
  5. After vertical surfaces are stripped of formwork, slab edges must be finished prior to curing.
  6. 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.
  7. 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
SA
NCC Variation Type
Replacement
NCC SPTC Current
Concrete

Concrete must comply with the following:

  1. 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.
  2. Water must not be added to the mix to increase the slump to a value in excess of that specified.
  3. 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.

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

  1. welded wire reinforcing fabric; or
  2. trench mesh; or
  3. 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—

  1. two strips of 3-L8TM; or
  2. one strip of 3-L11TM; or
  3. 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—

  1. 40 mm to unprotected ground; and
  2. 30 mm to a membrane in contact with the ground; and
  3. 20 mm to an internal surface; and
  4. 40 mm to external exposure.

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

(7) Reinforcement must be placed as follows:

  1. All reinforcement must be firmly fixed in place to prevent it moving during concreting operations.
  2. Reinforcement must be supported off the ground or the forms by bar chairs made from wire, concrete or plastic.
  3. When using wire chairs, the minimum concrete cover (see (5)) to the uncoated portion of the chair must be obtained.
  4. Wire chairs on soft ground or plastic membrane must be placed on flat bases.
  5. Bar chairs must be spaced at not more than 800 mm centres for steel fabric.
Table 4.2.11a Alternative mesh/reinforcing bar sizes
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
Table Notes
  1. Where necessary, 2 layers of mesh may be used.
  2. L11TM and L12TM may be replaced by RL1118 and RL1218 mesh respectively.
  3. L11TM may be replaced by two layers of L8TM.
Table 4.2.11b Minimum lap for reinforcement
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
Figure 4.2.11a Splice, L and T intersections
image-4-2-11a-splice-l-and-t-intersections.svg
Figure 4.2.11b Reinforcing for re-entrant corners
image-4-2-11b-reinforcing-for-re-entrant-corners.svg

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.

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

  1. 4.2.13 for footings for stumps; and
  2. 4.2.14 for stiffened rafts on Class A, S and M sites; and
  3. 4.2.15 for strip footing systems on Class A, S and M sites; and
  4. 4.2.16 for footing slabs on Class A sites; and
  5. 4.2.17 for footings for single leaf masonry, mixed construction and earth retaining walls; and
  6. 4.2.18 for footings for fireplaces on Class A and S sites; and
  7. 4.2.19 for shrinkage control; and
  8. 4.2.20 for concentrated loads; and
  9. 4.2.21 for minimum edge beam dimensions; and
  10. 4.2.22 for recessed areas of slabs.

(1) Footings for stumps must comply with—

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

(2) Concrete stumps must—

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

(3) Steel stumps must be—

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

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

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

(5) Stumps must be braced—

  1. by a full perimeter masonry base; or
  2. for concrete stumps — in accordance with AS 3600; or
  3. for steel stumps — in accordance with AS 4100; or
  4. 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.

Table 4.2.13a Stumps supporting single storey timber floor and metal roof
Floor load area (m2) Dimension (mm) Roof load area (m2)
0 6 12
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
Table Notes
  1. 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.
  2. Load combinations for ULS included are 1.35G and 1.2G + 1.5Q for stumps and G + 0.5Q for pad footings.
  3. Minimum bearing pressure is 100 kPa for pad footings.
  4. For pad footings founded on rock, the width or diameter may be reduced by half but not less than 250 mm x 250 mm or 300 mm diameter.
  5. Stumps are assumed to be braced and simply-supported at both ends with an effective length factor of 1.
  6. A maximum load eccentricity of length/100 has been accounted for in the stumps.
  7. A roof load area of “0” must be used for stumps not supporting roof loads.
  8. The length of wall load allowed for is equal to the square root of the floor area.
Table 4.2.13b Stumps supporting single storey tiled floor and tiled roof
Floor load area (m2) Dimension (mm) Roof load area (m2)
0 6 12
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
Table Notes
  1. 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.
  2. Load combinations for ULS included are 1.35G and 1.2G + 1.5Q for stumps and G + 0.5Q for pad footings.
  3. Minimum bearing pressure is 100 kPa for pad footings.
  4. For pad footings founded on rock, the width or diameter may be reduced by half but not less than 250 mm x 250 mm or 300 mm diameter.
  5. Stumps are assumed to be braced and simply-supported at both ends with an effective length factor of 1.
  6. A maximum load eccentricity of length/100 has been accounted for in the stumps.
  7. A roof load area of “0” must be used for stumps not supporting roof loads.
  8. The length of wall load allowed for is equal to the square root of the floor area.
Table 4.2.13c Stumps supporting double storey timber floor and metal roof
Floor load area (m2) Dimension (mm) Roof load area (m2)
0 6 12
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 Notes
  1. 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.
  2. Load combinations for ULS included are 1.35G and 1.2G + 1.5Q for stumps and G + 0.5Q for pad footings.
  3. Minimum bearing pressure is 100 kPa for pad footings.
  4. For pad footings founded on rock, the width or diameter may be reduced by half but not less than 250 mm x 250 mm or 300 mm diameter.
  5. Stumps are assumed to be braced and simply-supported at both ends with an effective length factor of 1.
  6. A maximum load eccentricity of length/100 has been accounted for in the stumps.
  7. A roof load area of “0” must be used for stumps not supporting roof loads.
  8. The length of wall load allowed for is equal to the square root of the floor area.
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)
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 fy = 350 MPa 100 x 100 x 2.0 3 3000 3000 3000
Steel fy = 350 MPa 100 x 100 x 2.0 8 3000 3000 3000
Steel fy = 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
  1. 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.
  2. Load combinations for ULS included are 1.35G and 1.2G + 1.5Q for stumps and G + 0.5Q for pad footings.
  3. Minimum bearing pressure is 100 kPa for pad footings.
  4. Stumps are assumed to be braced and simply-supported at both ends with an effective length factor of 1.
  5. A maximum load eccentricity of length/100 has been accounted for in the stumps.
  6. A roof load area of “0” must be used for stumps not supporting roof loads.
  7. 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)
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 fy = 350 MPa 100 x 100 x 2.0 3 3000 3000 3000
Steel fy = 350 MPa 100 x 100 x 2.0 8 3000 3000 3000
Steel fy = 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
  1. 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.
  2. Load combinations for ULS included are 1.35G and 1.2G + 1.5Q for stumps and G + 0.5Q for pad footings.
  3. Minimum bearing pressure is 100 kPa for pad footings.
  4. Stumps are assumed to be braced and simply-supported at both ends with an effective length factor of 1.
  5. A maximum load eccentricity of length/100 has been accounted for in the stumps.
  6. A roof load area of “0” must be used for stumps not supporting roof loads.
  7. 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)
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 fy = 350 MPa 100 x 100 x 2.0 3 3000 3000 3000
Steel fy = 350 MPa 100 x 100 x 2.0 8 3000 3000 3000
Steel fy = 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
  1. 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.
  2. Load combinations for ULS included are 1.35G and 1.2G + 1.5Q for stumps and G + 0.5Q for pad footings.
  3. Minimum bearing pressure is 100 kPa for pad footings.
  4. Stumps are assumed to be braced and simply-supported at both ends with an effective length factor of 1.
  5. A maximum load eccentricity of length/100 has been accounted for in the stumps.
  6. A roof load area of “0” must be used for stumps not supporting roof loads.
  7. The length of wall load allowed for is equal to the square root of the floor area.
Table 4.2.13g Minimum dimensions of circular and square pad footings for clad frame, Class A and S sites
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
Table Notes
  1. The effective area supported by a pad footing is the sum of—
    1. the supported floor area; and
    2. the supported roof area (if applicable); and
    3. half the supported wall area in elevation (if applicable).
  2. The width or diameter can be reduced to one half the above footings on rock.
  3. The pad footings must be constructed in concrete.
  4. Pad footing sizes must also apply to footings supporting roof and floor loads only.
  5. The foundation must provide an allowable bearing pressure of not less than 100 kPa.
  6. The excavation must be backfilled with manually rodded tamped soil, or the footing thickness shall be increased by 50 mm.
  7. Where stump pad footings provide resistance to horizontal or uplift forces, the minimum size of the footing must comply with AS 2870.
  8. Braced stumps must comply with 4.2.13(5).
  9. For masonry piers, strip footings complying with 4.2.15 for masonry can be used in lieu of pad footings.
Figure 4.2.13 Pad footings for clad frame, Class A and S sites
image-4-2-13-pad-footings-clad-frame-class-a-and-s-sites.svg
Figure Notes
  1. For minimum pad footing dimensions t and D, see Table 4.2.13g.
  2. For tamped fill or thickened concrete pads, see Note 6 to Table 4.2.13g.

Footing and stiffened raft slabs must comply with—

  1. For Class A and S sites — Tables 4.2.14a, 4.2.14b and Figure 4.2.14a; and
  2. For Class M sites — Table 4.2.14c and Figure 4.2.14b.
Table 4.2.14a Reinforcement for stiffened raft footings for Class A sites
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
Table Notes
  1. Internal and external edge beams must be arranged to form an integral structural grid (see clauses 5.3.8 and 5.3.9 of AS 2870).
  2. A 10% increase in spacings is permitted where the spacing in the other direction is 20% less than that specified.
  3. Where external beams are wider than 300 mm, an extra bottom bar or equivalent of the same bar size is required for each 100 mm additional width.
  4. Where a reinforced single leaf masonry wall is constructed directly above and structurally connected to a concrete edge beam, the beam may be reduced to 300 mm wide by 300 mm deep and reinforced with 3–L8TM reinforcement.
  5. Alternative reinforcement sizes must comply with AS 2870.
  6. Internal beam details and spacings must comply with Figure 4.2.14a or Figure 4.2.14b.
Table 4.2.14b Reinforcement for stiffened raft footings for Class S sites
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
Table Notes
  1. Internal and external edge beams must be arranged to form an integral structural grid (see clauses 5.3.8 and 5.3.9 of AS 2870).
  2. A 10% increase in spacings is permitted where the spacing in the other direction is 20% less than that specified.
  3. Where external beams are wider than 300 mm, an extra bottom bar or equivalent of the same bar size is required for each 100 mm additional width.
  4. Where a reinforced single leaf masonry wall is constructed directly above and structurally connected to a concrete edge beam, the beam may be reduced to 300 mm wide by 300 mm deep and reinforced with 3–L8TM reinforcement.
  5. Alternative reinforcement sizes must comply with AS 2870.
  6. Internal beam details and spacings must comply with Figure 4.2.14a or Figure 4.2.14b.
Table 4.2.14c Reinforcement for stiffened raft footings for Class M sites
Type of construction Depth (D) (mm) Bottom reinf. Max. spacing c/l to c/l Slab mesh
Clad frame 300 3-L11TM 6.0Note 2 SL72
Articulated masonry veneer 400 3-L11TM 6.0Note 2 SL72
Masonry veneer 400 3-L11TM 5.0Note 2 SL72
Articulated full masonry 500 3-L12TM 4.0 SL82
Full masonry 850 3-N16 4.0 SL92
Table Notes
  1. Internal and external edge beams must be arranged to form an integral structural grid (see clauses 5.3.8 and 5.3.9 of AS 2870).
  2. A 10% increase in spacings is permitted where the spacing in the other direction is 20% less than that specified.
  3. Where external beams are wider than 300 mm, an extra bottom bar or equivalent of the same bar size is required for each 100 mm additional width.
  4. Where a reinforced single leaf masonry wall is constructed directly above and structurally connected to a concrete edge beam, the beam may be reduced to 300 mm wide by 300 mm deep and reinforced with 3–L8TM reinforcement.
  5. Alternative reinforcement sizes must comply with AS 2870.
  6. Internal beam details and spacings must comply with Figure 4.2.14b.
Figure 4.2.14a Footing slab and stiffened raft slab details for Class A and S sites
image-4-2-14a-footing-slab-and-stiffened-raft-details-class-a-and-s-sites.svg
Figure 4.2.14b Footing slab and stiffened raft slab details for Class M sites
image-4-2-14b-footing-slab-and-stiffened-raft-details-class-m-sites.svg

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

  1. for Class A and S sites — Tables 4.2.15a, 4.2.15b and Figure 4.2.15a; and
  2. for Class M sites — Table 4.2.15c and Figure 4.2.15b.
Table 4.2.15a Dimensions and reinforcement for strip footing systems for Class A sites
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
Table Notes
  1. All masonry walls must be supported on strip footings.
  2. Internal strip footings must be of the same proportions as the external footings and run from external footing to external footing. ‘Side slip joints’ consisting of a double layer of polyethylene must be provided at the sides of the footing only.
  3. Infill floors may be concrete slabs, brick paving, stone flags or compacted and stabilised earth. For concrete slab infill panels, mesh may be required to control shrinkage in slab panels and around openings or restrained regions. Concrete infill slabs must use a minimum of SL62 mesh to control shrinkage (see also 4.2.19).
  4. Where footings are wider than the specified width, an extra bottom bar or equivalent of the same bar size is required for each 100 mm additional width. If strip footings deeper than those required are used, the reinforcement must be increased to match that specified for the deepened proportions.
  5. The measurement of Df is greater or equal to D plus 75 mm.
  6. Alternative reinforcing sizes must comply with AS 2870.
Table 4.2.15b Dimensions and reinforcement for strip footing systems for Class S sites
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
Table Notes
  1. All masonry walls must be supported on strip footings.
  2. Internal strip footings must be of the same proportions as the external footings and run from external footing to external footing. ‘Side slip joints’ consisting of a double layer of polyethylene must be provided at the sides of the footing only.
  3. Infill floors may be concrete slabs, brick paving, stone flags or compacted and stabilised earth. For concrete slab infill panels, mesh may be required to control shrinkage in slab panels and around openings or restrained regions. Concrete infill slabs must use a minimum of SL62 mesh to control shrinkage (see also 4.2.19).
  4. Where footings are wider than the specified width, an extra bottom bar or equivalent of the same bar size is required for each 100 mm additional width. If strip footings deeper than those required are used, the reinforcement must be increased to match that specified for the deepened proportions.
  5. The measurement of Df is greater or equal to D plus 75 mm.
  6. Alternative reinforcing sizes must comply with AS 2870.
Table 4.2.15c Dimensions and reinforcement for strip footing systems for Class M sites
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
Table Notes
  1. All masonry walls must be supported on strip footings.
  2. For beams 700 mm or deeper, as specified in the table above, internal footings must be provided at no more than 6 m centres and at re-entrant corners to continue footings to the opposite external footing. Internal strip footings must be of the same proportions as the external footings and run from external footing to external footing. ‘Side slip joints’ consisting of a double layer of polyethylene must be provided at the sides of the footing only.
  3. Infill floors must only be used for Class A and S sites.
  4. Where footings are wider than the specified width, an extra bottom bar or equivalent of the same bar size is required for each 100 mm additional width. If strip footings deeper than those required are used, the reinforcement must be increased to match that specified for the deepened proportions.
  5. The measurement of Df is greater or equal to D plus 75 mm.
  6. Alternative reinforcing sizes must comply with AS 2870.
  7. For Class M articulated full masonry and full masonry, internal strip footings must be of the same proportions as the external footing and run from external footing to external footing.
Figure 4.2.15a Strip footing systems for Class A and S sites
image-4-2-15a-strip-footing-system-class-a-and-s-sites.svg
Figure Notes

See Notes to Tables 4.2.15a and 4.2.15b.

Figure 4.2.15b Strip footing system for Class M sites
image-4-2-15b-strip-footing-system-class-m-sites.svg
Figure Notes

See Notes Tables 4.2.15a, 4.2.15b and 4.2.15c.

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

  1. Clad frame.
  2. Articulated masonry.
  3. Masonry veneer.
  4. Articulated full masonry.
  5. Full masonry.
Figure 4.2.16 Footing slabs for Class A sites suitable for clad frame, articulated masonry veneer, masonry veneer, articulated full masonry and full masonry
image-4-2-16-footing-slabs-class-a-sites-clad-frame-masonry.svg
Figure Notes
  1. Use SL63 when slab length is less than 12 m.
  2. Use SL62 when slab length is less than 18 m.
  3. In parts of Western Australia (around Perth) and other locations where the site consists of extremely stable sands, and where specified by a professional engineer, the slab thickness may be reduced to 85 mm and reinforced as follows:
    1. Use SL53 when slab length is less than or equal to 12 m.
  4. Dune sands may require compaction.

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:

  1. Single leaf masonry.
  2. Mixed construction.
  3. Earth wall structures.
Table 4.2.17a Equivalent wall construction: single leaf masonry
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
Table 4.2.17b Equivalent wall construction: mixed construction
Actual construction: external walls Actual construction: internal walls Equivalent wall construction
Full masonry Framed Articulated full masonry
Articulated full masonry Framed Masonry veneer
Table 4.2.17c Equivalent wall construction: earth wall construction
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.

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

  1. 150 mm thick for single storey (one trafficable floor and a wall height not more than 4.2 m) construction; and
  2. 200 mm thick for 2 storey (two trafficable floors and a wall height not more than 8 m) construction; and
  3. reinforced top and bottom with SL72 mesh; and
  4. 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.

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—

  1. 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
  2. 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
  3. the placement of floor covering must be delayed for not less than 3 months after the concrete has been poured.

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

  1. 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
  2. be centred under the structural steel column; and
  3. have SL72 reinforcement with a minimum 50 mm of concrete cover (see Figure 4.2.20).
Table 4.2.20a Localised thickening under concentrated load — tiled floor and tiled roof — roof load area = 0 m2
Localised thickening Maximum floor load area (m2)
4 10 16
Square thickening size (mm) 450 x 450 650 x 650 850 x 850
Thickening depth (mm) 250 350 400
Table Notes
  1. Load accounted for includes 0.98 kPa permanent tiled floor, 0.85 kPa permanent tiled roof, 1.16 kN/m permanent wall, permanent member self-weight, 1.5 kPa or 1.1 kN imposed floor and 0.25 kPa imposed roof.
  2. Load combinations included are G + 0.5Q for ULS.
  3. Minimum bearing pressure is 100 kPa for pad footings.
  4. A roof load area of “0” must be used for footings not supporting roof loads.
  5. The length of wall allowed for is equal to the square root of the floor area.
Table 4.2.20b Localised thickening under concentrated load — tiled floor and tiled roof — roof load area = maximum 9 m2
Localised thickening Maximum floor load area (m2)
4 10 16
Square thickening size (mm) 650 x 650 800 x 800 950 x 950
Thickening depth (mm) 350 400 450
Table Notes
  1. Load accounted for includes 0.98 kPa permanent tiled floor, 0.85 kPa permanent tiled roof, 1.16 kN/m permanent wall, permanent member self-weight, 1.5 kPa or 1.1 kN imposed floor and 0.25 kPa imposed roof.
  2. Load combinations included are G + 0.5Q for ULS.
  3. Minimum bearing pressure is 1000 kPa for pad footings.
  4. The length of wall allowed for is equal to the square root of the floor area.
Table 4.2.20c Localised thickening under concentrated load — tiled floor and tiled roof — roof load area = maximum 18 m2
Localised thickening Maximum floor load area (m2)
4 10 16
Square thickening size (mm) 750 x 750 900 x 900 1000 x 1000
Thickening depth (mm) 400 450 500
Table Notes
  1. Load accounted for includes 0.98 kPa permanent tiled floor, 0.85 kPa permanent tiled roof, 1.16 kN/m permanent wall, permanent member self-weight, 1.5 kPa or 1.1 kN imposed floor and 0.25 kPa imposed roof.
  2. Load combinations included are G + 0.5Q for ULS.
  3. Minimum bearing pressure is 1000 kPa for pad footings.
  4. The length of wall allowed for is equal to the square root of the floor area.
Table 4.2.20d Localised thickening under concentrated load — timber floor and metal roof — roof load area = 0 m2
Localised thickening Maximum floor load area (m2)
4 10 16
Square thickening size (mm) 400 x 400 600 x 600 750 x 750
Thickening depth (mm) 250 300 350
Table Notes
  1. Load accounted for includes 0.53 kPa permanent timber floor, 0.4 kPa permanent metal roof, 1.16 kN/m permanent wall, permanent member self-weight, 1.5 kPa or 1.1 kN imposed floor and 0.25 kPa imposed roof.
  2. Load combinations included are G + 0.5Q for ULS.
  3. Minimum bearing pressure is 1000 kPa for pad footings.
  4. A roof load area of “0” must be used for footings not supporting roof loads.
  5. The length of wall allowed for is equal to the square root of the floor area.
Table 4.2.20e Localised thickening under concentrated load — timber floor and metal roof — roof load area = maximum 9 m2
Localised thickening Maximum floor load area (m2)
4 10 16
Square thickening size (mm) 500 x 500 700 x 700 800 x 800
Thickening depth (mm) 300 350 400
Table Notes
  1. Load accounted for includes 0.53 kPa permanent timber floor, 0.4 kPa permanent metal roof, 1.16 kN/m permanent wall, permanent member self-weight, 1.5 kPa or 1.1 kN imposed floor and 0.25 kPa imposed roof.
  2. Load combinations included are G + 0.5Q for ULS.
  3. Minimum bearing pressure is 1000 kPa for pad footings.
  4. The length of wall allowed for is equal to the square root of the floor area.
Table 4.2.20f Localised thickening under concentrated load — timber floor and metal roof — roof load area = maximum 18 m2
Localised thickening Maximum floor load area (m2)
4 10 16
Square thickening size (mm) 600 x 600 750 x 750 850 x 850
Thickening depth (mm) 300 400 450
Table Notes
  1. Load accounted for includes 0.53 kPa permanent timber floor, 0.4 kPa permanent metal roof, 1.16 kN/m permanent wall, permanent member self-weight, 1.5 kPa or 1.1 kN imposed floor and 0.25 kPa imposed roof.
  2. Load combinations included are G + 0.5Q for ULS.
  3. Minimum bearing pressure is 1000 kPa for pad footings.
  4. The length of wall allowed for is equal to the square root of the floor area.
Figure 4.2.20 Localised thickening for concentrated loads
image-4-2-20-localised-thickening-for-concentrated-loads.svg

For footing slabs, the width of the edge beam at the base of the rebate must not be less than 200 mm, except that if R10 or N10 ties at 900 mm spacing (or equivalent) are provided to resist vertical forces, the width of the edge beam at the base of the rebate can be reduced to 150 mm.

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

  1. 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).
  2. 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).

Figure 4.2.22a Recess depths (d) less than or equal to nominal slab thickness
image-4-2-22a-recess-depths-less-than-or-equal-to-nominal-slab-thickness.svg
Figure 4.2.22b Recess depths (d) greater than nominal slab thickness
image-4-2-22b-recess-depths-greater-than-nominal-slab-thickness.svg