2870_AMD3

ISBN 0 7337 4936 4

AS 2870/Amdt 3/2002-11-22

STANDARDS AUSTRALIA

Amendment No. 3

to

AS 2870—1996

Residential slabs and footings—Construction

REVISED TEXT

The 1996 edition of AS 2870 is amended as follows; the amendments should be inserted in the appropriate

places.

SUMMARY: This Amendment applies to the Preface, Clauses 1.6, 1.9, 3.1.1, 3.2, 3.3, 3.4, 3.6.2, 4.5.1, 5.2.2,

5.3.2, 5.3.4, 5.3.6, 5.3.7, 6.4.2, 6.4.5, Figures 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 6.3, G1 and Table 3.2.

Published on 22 November 2002.

At the time of publishing Amendment No. 3 to AS 2870 was not referenced in the Building Code of Australia.

Page 2 Preface

Insert the following after the last paragraph:

‘The purpose of Amendment No. 3 to AS 2870—1996 is to bring the Standard into line with

the nomenclature now in use in Australia for the specification of reinforcing mesh and bars.

AS/NZS 4671, Steel reinforcing materials, was published in April 2001. It describes the

proportion of reinforcing mesh and bars now distributed in Australia. AS/NZS 4671 adopts

the nomenclature, which is different from that used in previous editions of AS 2870.

AS/NZS 4671 has specific relevance to grade 500L mesh and 500N bars, materials that are

currently the subject of ongoing research, particularly with regard to the issue of ductility.

Standards Australia Committee BD-025 is evaluating the results of this research. The

committee may find it appropriate to issue further amendments to this Standard should

issues of ductility be found to impact on the performance levels of footings designed in

accordance with the Standard.’

Page 7 Clause 1.6

Delete the following:

AS 1289.F3.3 Part F—Soil strength and consolidation tests—Determination of the

penetration resistance of a soil with a Perth sand penetrometer

AS 1302 Steel reinforcing bars for concrete

AS 1304 Welded wire reinforcing fabric for concrete

AS 3660 Protection of buildings from subterranean termites

AS 3660.1 Part 1: New buildings

and insert the following:

AS 1289.6.3.3 Method 6.3.3: Soil strength and consolidation tests—Determination of

the penetration resistance of a soil—Perth sand

penetrometer test

AS 3500 National Plumbing and Drainage Code

AS 3500.2 Part 2: Sanitary plumbing and sanitary drainage

AS 3660 Termite management

AS 3660.1 Part 1: New building work

AS/NZS 4671 Steel reinforcing materials

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Page 11 Clause 1.9

Delete Clause 1.9 and replace with the following:

‘1.9 REINFORCEMENT DESIGNATION

1.9.1 Trench mesh For the purposes of this Standard, trench mesh is designated as

x-L8TM, x-L11TM or x-L12TM, where x is the number of main longitudinal bars required

of the appropriate trench mesh L8TM, L11TM or L12TM. Trench mesh shall comply with

AS/NZS 4671.

1.9.2 Square mesh SL62, SL72, SL82, SL92 or SL102 shall comply with AS/NZS 4671.

SL53 and SL63 refer to square mesh similar to stock mesh specified in AS/NZS 4761, but

with 5 mm bars and 6 mm bar at 300 mm centres respectively, and with the bars complying

with the requirements for grade 500L in accordance with AS/NZS 4671.

1.9.3 Reinforcing bars Reinforcing bars shall comply with AS/NZS 4671 Grade 500N,

and are specified as x-N12, x-N16, or x-N20, where x is the number of bars.’

Page 18 Clause 3.1.1(b)

Delete ‘25 m’ and replace with ‘30 m’.

Page 18 Clause 3.1.1

Add new item (j)

‘(j) On class M, M-D, H or H-D sites, the construction of a footing system for a single

building comprising any combination of two or more designs taken from Figures 3.1,

3.4, 3.5 or 3.6.’

Page 19 Clause 3.2(b)

Delete ‘Y12’ and replace with ‘N12’

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Page 20 Figure 3.1 (in part)

Delete existing figure and replace with the following:

DIMENSIONS IN MILLIMETRES

Edge and internal beams

(see Note 1) Slab mesh

Site

class Type of construction Depth

(D)

mm

Bottom

reinfor-

cement

Maximum

spacing

centre to

centre (m)

Slab

length

<18m

Slab

length

≥≥≥≥18 &

<25m

Slab

length

≥≥≥≥25m&

<30m

Class A Clad frame 300 3-L8TM — SL72 SL82 SL92 Articulated masonry 300 3-L8TM — SL72 SL82 SL92

Masonry veneer 300 3-L8TM — SL72 SL82 SL92

Articulated full masonry 400 3-L8TM — SL72 SL82 SL92

Full masonry 400 3-L8TM — SL72 SL82 SL92

Class S Clad frame 300 3-L8TM — SL72 SL82 SL92 Articulated masonry 300 3-L8TM — SL72 SL82 SL92

Masonry veneer 300 3-L11TM — SL72 SL82 SL92

Articulated full masonry 400 3-L11TM — SL72 SL82 SL92

Full masonry 450 3-L11TM 5.0(Note 2) SL82 SL82 SL92

Class M Clad frame 300 3-L11TM 6.0(Note 2) SL72 SL82 SL92 Articulated masonry 400 3-L11TM 6.0(Note 2) SL72 SL82 SL92

Masonry veneer 400 3-L11TM 5.0(Note 2) SL72 SL82 SL92

Articulated full masonry 500 3-L12TM 4.0 SL82 SL82 SL92

Full masonry 800 3-N16 4.0 SL92 SL92 SL92

Class Clad frame 400 3-L11TM 5.0(Note 2) SL72 SL82 SL92M –D Articulated masonry 400 3-L11TM 4.0 SL72 SL82 SL92

Masonry veneer 500 3-L12TM 4.0 SL82 SL82 SL92

Articulated full masonry 625 3-L12TM 4.0 SL92 SL92 SL92

Full masonry — — — — — —

Class H Clad frame 400 3-L11TM 5.0(Note 2) SL72 SL82 SL92 Articulated masonry 500 3-L12TM 4.0 SL82 SL82 SL92

Masonry veneer 700 3-N16 4.0 SL92 SL92 SL92

Articulated full masonry 1 000 4-N16 4.0 SL102 SL102 SL102


Class Clad frame 500 3-L11TM 4.0 SL82 SL82 SL92H-D Articulated masonry 600 3-L12TM 4.0 SL92 SL92 SL92

Masonry veneer — — — — — —

Articulated full masonry

(See Note 6)

1 200 4-N16 4.0 SL102 SL102 SL102


FIGURE 3.1 (in part) STIFFENED RAFT SITE CLASSES A, S, M, M-D, H, H-D

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Page 21 Figure 3.1 (in part) Notes

1 Delete ‘R10’ in Note 5 and replace with ‘R10 or N10’

2 Delete Table in Note 8 and replace with the following:

Specified slab mesh

SL102 SL92 SL82 Alternative slab

mesh

Additional reinforcement at top of beams

SL92 3-L11TM — —

SL82 3-N16 3-L11TM —

SL72 4-N16 4-L12TM 2-L12TM

3 Delete ‘3-8TM’ in Note 9 and replace with ‘3-L8TM’

Page 22 Figure 3.2

Delete existing figure and notes and replace with the following:

NOTES:

1 Use SL63 when maximum slab length ≤12 000.

Use SL62 when maximum slab length >12 000 and <18 000.

Use SL72 when maximum slab length ≥18 000 and <25 000.


2 In Western Australia, for slabs under 25 m in length, where specified by an appropriately qualified

engineer, the slab thickness may be reduced to 85 mm with reinforcement as specified below. All other

details remain the same.

Use SL53 when maximum slab length ≤12 000.

Use SL63 when maximum slab length >12 000 and <18 000.


3 Dune sands may require compaction.


FIGURE 3.2 FOOTING SLAB FOR CLASS A SITES FOR CLAD FRAME, ARTICULATED

MASONRY VENEER, MASONRY VENEER, ARTICULATED FULL MASONRY OR FULL

MASONRY

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Page 23 Figure 3.3


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Slab mesh

Site class and type of construction

Beam

depth

mm

Bar size beam

reinforcement Slab length

<25m

Slab length

≥≥≥≥25m & <30m

Class A

Clad frame, articulated masonry

veneer and masonry veneer

260 N-12 SL72 SL82

Single-storey articulated full masonry

and single-storey full masonry

310 N-12 SL72 SL82

Class S



260 N-12 SL72 SL82

Single-storey articulated full masonry 310 N-12 SL72 SL82

Class M



310 N-12 SL72 SL82

Class M-D

Clad frame and articulated masonry

veneer

310 N-12 SL72 SL82

Class H

Clad frame 310 N-12 SL72 SL82

Articulated masonry veneer 385 N-12 SL82 SL92

Class H-D

Clad frame 385 N-16 SL72 SL82

Articulated masonry veneer 385 N-16 SL82 SL92


FIGURE 3.4 (in part) WAFFLE RAFT

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Add the following to the Notes:

‘5 Internal and edge beams should be arranged to maintain continuity at re-entrant corners.

6 Modifications to the details given in this figure shall not be undertaken without engineering design carried

out in accordance with Section 4.’

Page 26 Figure 3.5

Delete existing figure and Notes and replace with the following:

NOTES:

1 The reinforcement of the cavity shall consist of N12 bars at 400 centres in each direction anchored into

both the footing and the slab. The cavity shall be filled with well compacted 20 MPa concrete, or grout in

accordance with AS 3700. Single-leaf reinforced masonry may also be used.

2 Horizontal construction joints are permitted between the beams and the slab, provided the concrete-to-

concrete joint is at least 150 mm wide and is transversed by R10 or N10 fitments at 600 mm centres.

3 Beams shall be spaced in accordance with Figure 3.1.

4 Where local practice indicates satisfactory performance, the internal stiffening beams may be omitted when

all internal partition walls are of non-load-bearing framed construction.

5 Construction details are given in Section 6.


FIGURE 3.5 STIFFENED SLAB WITH DEEP EDGE BEAM FOR MASONRY VENEER

AND ARTICULATED MASONRY VENEER CLASS M SITE

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1 Delete table associated with Figure 3.6 (in part) and replace with the following:

Site class Type of construction D B Reinforce-

ment Ds Ls

Class A Clad frame 300 300 3-L8TM 400 —

Articulated masonry veneer 300 300 3-L8TM 400 —

Masonry veneer 300 300 3-L8TM 400 —

Articulated full masonry 300 400 4-L8TM 400 —

Full masonry 300 400 4-L8TM 400 —

Class S Clad frame 400 300 3-L8TM 400 —




Full masonry 500 400 4-L11TM 400 —

Class M Clad frame 400 300 3-L11TM 500 —




Full masonry 900 (Note 2) 400 4-L12TM 500 —

Class M-D Clad frame 500 300 3-L11TM 800 —


Masonry veneer 700 (Note 2) 300 3-N16 800 —

Articulated full masonry 1 100 (Note 2) 400 4-N16 800 —

Class H Clad frame 500 300 3-L11TM 1 000 ≥2 400

Articulated masonry veneer 600 300 3-L12TM 1 000 ≥2 400

Masonry veneer 850 (Note 2) 300 3-N16 1 000 ≥2 400

Articulated full masonry 1 100 (Note 2) 400 4-N16 1 000 ≥2 400

2 Delete last sentence of Note 6 and replace with the following:

‘SL62 should normally be provided (see also Clause 5.3.7).’

Page 30 Clause 3.3

Delete Clause 3.3 and replace with the following:

‘The bar sizes given in Table 3.2 are deemed to comply with the requirements for trench

mesh reinforcement in beams and footings. L11TM and L12TM may be replaced by

RL1118 and RL1218 mesh respectively. Two layers of L8TM may be used as a replacement

for L11TM. Where a single layer of trench mesh would be too wide for the footing or beam,

multiple layers, bundled together, or equivalent reinforcement shall be used.

Alternative arrangements of beam or footing reinforcement may be used, if the flexural

strength of the section is unimpaired.’

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Page 30 Table 3.2

Delete Table and replace with the following:

TABLE 3.2

REINFORCING BAR SIZES DEEMED TO BE EQUIVALENT

TO TRENCH MESH REINFORCEMENT

Trench mesh Area of steel

mm2

Bar alternative Trench mesh

alternative

2-L8TM 91 2-N10 or 1-N12 —

3-L8TM 136 2-N10 or 2-N12 —

4-L8TM 182 2-N12 2-L11TM

5-L8TM 227 2-N12 3-L11TM

2-L11TM 180 1-N16 or 2-N12 2 x 2-L8TM

3-L11TM 270 3-N12 2 x 3-L8TM

4-L11TM 360 2-N16 2 x 4-L8TM

2-12TM 222 2-N12 3-L11TM

3-12TM 333 3-N12 4-L11TM

4-12TM 444 4-N12 5-L11TM

Page 30 Clause 3.4(b)

Delete both references to ‘F72’ and replace with ‘SL72’.


Delete ‘F72’ and replace with ‘SL72’.


1 Delete the value ‘80 mm’ in the table in the ‘ys’ row and replace with ‘100 mm’.

2 Delete ‘25 m’ from the ‘Span’ row and replace with ‘30 m’.

3 Delete the second sentence from the paragraph under the table and replace with the

following:

‘It may be used to override the beam spacing and reinforcement provisions, provided that

the slab mesh is not less than SL72 for slab spans <18 m; SL82 for spans ≥18 m and <25 m;

and SL92 for spans ≥25 m and provided that the ductility requirements of Clause 4.4(e) are

satisfied.’

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1 Delete title of Clause and replace with ‘Specific requirements for slabs on Class 1

buildings’.

2 Insert ‘on a Class 1 building’ after ‘minimum height of the slab’.

3 Delete Note to Clause and insert the following:

NOTES:

1 These minimum heights specified above are to the top of the finished ground, landscaping or

paving level.

2 The minimum height of the slab specified above is for the purpose of reducing the risk of

surface water penetrating the building.

3 In determining the slab height above ground level, consideration should be given to the

requirements of AS 3500.2, which requires a minimum height from the top of the overflow

gully riser to the lowest plumbing fixture connected to the drain. Similarly, consideration

should be given to AS 3700, which sets a minimum height from finished ground level, etc., to

the damp-proof coursing level and AS 3660.1, which gives a minimum height from finished

ground or paving levels to some termite barriers.

Page 37 Clause 5.3.2(a)

Delete ‘fabric’ in the second sentence and replace with ‘mesh’.


Delete the first line and replace with the following:

‘Raft or slab mesh shall be lapped by one full panel of mesh so that the two’

Page 39 Clause 5.3.4(d)

Delete reference to ‘R10’ and replace with ‘R10 or N10’.


Delete the first sentence and replace with:

‘Hot water heating pipes may be embedded in a slab, provided that the slab thickness is

increased by 25 mm and an increase made in the mesh of one level; for example, SL72 for

SL62, SL82 for SL72 and SL92 for SL82.’

Page 41 Clause 5.3.7(a)(i)

Delete ‘F92’ and replace with ‘SL92’


1 Delete ‘3-8TM’ and replace with ‘3-L8TM’

2 Delete ‘3-11TM’ and replace with ‘3-L11TM’

3 Delete ‘3Y12’ and replace with ‘3-N12’


Delete ‘AS 1289.F3.3’ and replace with ‘AS 1289.6.3.3’


Delete ‘F82’ and replace with ‘SL82’

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Delete ‘Y12’ and replace with ‘N12’

Page 49 Figure 6.3

Delete parts (c) and (d) of the existing figure and the table and replace with the following:

Wall height (h) Wall construction

h < 450 Single width masonry with engaged piers at 1200 mm

centres

h ≤ 750 Double width masonry wall 230 mm thick. Solid or

filled concrete block wall 200 mm thick

h ≤ 1 500

Double width masonry with a 75 mm filled cavity or a

200 mm filled block wall reinforced with tied N12 bars

at 400 mm spacing horizontally and vertically. For

h > 1200 mm the wall and footing shall be tied to the

slab. Cavity filling shall be well compacted 20 MPa

concrete or grout in accordance with AS 3700.

h > 1 500 Designed in accordance with engineering principles

NOTE: Drainage provisions should be made.

Page 71 Figure G1

Delete the first table and replace with the following:

Footing beam details Pile details

Minimum driven depth of pile,

mm (See Note) Site

class

Df

mm

D

mm

Trench

mesh

Dowel pin

diameter ××××

length mm Clad frame and

masonry veneer

Articulated

full masonry

S 400 500 3-L11TM Not required 1 000 1 500

M 450 500 3-L12TM Not required 2 000 2 500

H 500 550 3-L12TM 20 × 800 2 500 3 000

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