Specification 2 Descriptions of elements referred to in Specification 1
S2C1
Scope
New for 2022
S2C2
Mortar for masonry
2019: Sch. 5 (Annex): 1.1
Masonry units of ashlar, calcium silicate, concrete or fired clay (including terracotta blocks) must be laid in cement mortar or composition mortar complying with the relevant provisions of AS 3700.
S2C3
Gypsum blocks
2019: Sch. 5 (Annex): 1.2
Gypsum blocks must be laid in gypsum-sand mortar or lime mortar.
S2C4
Gypsum-sand mortar and plaster
2019: Sch. 5 (Annex): 1.3
Gypsum-sand mortar and gypsum-sand plaster must consist of either—
- not more than 3 parts by volume of sand to 1 part by volume of gypsum; or
- if lime putty is added, not more than 2.5 parts by volume of sand to 1 part by volume of gypsum and not more than 5% of lime putty by volume of the mixed ingredients.
S2C5
Gypsum-perlite and gypsum-vermiculite plaster
2019: Sch. 5 (Annex): 1.4
Gypsum-perlite or gypsum-vermiculite plaster must be applied—
- in either one or 2 coats each in the proportions of 1 m3 of perlite or vermiculite to 640 kg of gypsum if the required thickness of the plaster is not more than 25 mm; and
- in 2 coats if the required thickness is more than 25 mm, the first in the proportions of 1 m3 of perlite or vermiculite to 800 kg of gypsum and the second in the proportions of 1 m3 of perlite or vermiculite to 530 kg of gypsum.
S2C6
Plaster of cement and sand or cement, lime and sand
2019: Sch. 5 (Annex): 1.5
S2C7
Plaster reinforcement
2019: Sch. 5 (Annex): 1.6
If plaster used as fire protection on walls is more than 19 mm thick—
- it must be reinforced with expanded metal lath that—
- has a mass per unit area of not less than 1.84 kg/m2; and
- has not fewer than 98 meshes per metre; and
- is protected against corrosion by galvanising or other suitable method; or
- it must be reinforced with 13 mm x 13 mm x 0.7 mm galvanised steel wire mesh securely fixed at a distance from the face of the wall of not less than ⅓ of the total thickness of the plaster.
S2C8
Ashlar stone masonry
2019: Sch. 5 (Annex): 2
Ashlar masonry must not be used in a part of the building containing more than 2 storeys, and must not be of—
- aplite, granite, granodiorite, quartz dacite, quartz diorite, quartz porphyrite or quartz porphyry; or
- conglomerate, quartzite or sandstone; or
- chert or flint; or
- limestone or marble.
S2C9
Dimensions of masonry
2019: Sch. 5 (Annex): 3
S2C10
Solid units
2019: Sch. 5 (Annex): 3.1
For masonry in which the amount of perforation or coring of the units does not exceed 25% by volume (based on the overall rectangular shape of the unit) the thickness of the wall must be calculated from the manufacturing dimensions of the units and the specified thickness of the joints between them as appropriate.
S2C11
Hollow units
2019: Sch. 5 (Annex): 3.2
For masonry in which the amount of perforation or coring of the units exceeds 25% by volume (based on the overall rectangular shape of the unit) the thickness of the wall must be calculated from the equivalent thicknesses of the units and the specified thickness of the joints between them as appropriate.
S2C12
Equivalent thickness
2019: Sch. 5 (Annex): 3.3
The equivalent thickness of a masonry unit is calculated by dividing the net volume by the area of one vertical face.
S2C13
Height-to-thickness ratio of certain walls
2019: Sch. 5 (Annex): 5
The ratio of height between lateral supports to overall thickness of a wall of ashlar, no-fines concrete, unreinforced concrete, solid gypsum blocks, gypsum-perlite or gypsum-vermiculite plaster on metal lath and channel, must not exceed—
- 20 for a loadbearing wall; or
- 27 for a non-loadbearing wall.
S2C14
Increase in thickness by plastering — walls
2019: Sch. 5 (Annex): 6.1
If a wall of ashlar, solid gypsum blocks or concrete is plastered on both sides to an equal thickness, the thickness of the wall for the purposes of Tables S1C2b and S1C2c (but not for the purposes of S2C5) may be increased by the thickness of the plaster on one side.
S2C15
Increase in thickness by plastering — columns
2019: Sch. 5 (Annex): 6.2
S2C16
Gypsum-perlite or gypsum-vermiculite plaster or metal lath — walls
2019: Sch. 5 (Annex): 7.1
In walls fabricated of gypsum-perlite or gypsum-vermiculite plaster on metal lath and channel—
- the lath must be securely wired to each side of 19 mm x 0.44 kg/m steel channels (used as studs) spaced at not more than 400 mm centres; and
- the gypsum-perlite or gypsum-vermiculite plaster must be applied symmetrically to each exposed side of the lath.
S2C17
Gypsum-perlite or gypsum-vermiculite plaster or metal lath — columns
2019: Sch. 5 (Annex): 7.2
- the lath must be fixed at not more than 600 mm centres vertically to steel furring channels, and—
- if the plaster is to be 35 mm thick or more — at least 12 mm clear of the column; or
- if the plaster is to be less than 35 mm thick — at least 6 mm clear of the column; or
- the plaster may be applied to self-furring lath with furring dimples to hold it not less than 10 mm clear of the column.
S2C18
Gypsum-perlite or gypsum-vermiculite plaster or metal lath — beams
2019: Sch. 5 (Annex): 7.3
For the fire protection of steel beams with gypsum-perlite or gypsum-vermiculite on metal lath—
- the lath must be fixed at not more than 600 mm centres to steel furring channels and at least 20 mm clear of the steel; and
- the thickness of the plaster must be measured from the back of the lath.
S2C19
Exposure of columns
2019: Sch. 5 (Annex): 8.1
A column incorporated in or in contact on one or more sides with a wall of solid masonry or concrete at least 100 mm thick may be considered to be exposed to fire on no more than 3 sides.
S2C20
Exposure of beams
2019: Sch. 5 (Annex): 8.2
A beam, open-web joist, girder or truss in direct and continuous contact with a concrete slab or a hollow block floor or roof may be considered to be exposed to fire on no more than 3 sides.
S2C21
Filling of column spaces
2019: Sch. 5 (Annex): 9
S2C22
Hollow terracotta blocks
2019: Sch. 5 (Annex): 10
The proportion of cored holes or perforations in a hollow terracotta block (based on the overall rectangular volume of the unit) must not exceed the following:
- For blocks up to 75 mm thick — 35%.
- For blocks more than 75 mm but not more than 100 mm thick — 40%.
- For blocks more than 100 mm — 50%.
S2C23
Reinforcing for column and beam protection — masonry
2019: Sch. 5 (Annex): 11.1
Masonry of calcium-silicate, fired clay and concrete for the protection of steel columns must have steel-wire or mesh reinforcement in every second course and lapped at the corners.
S2C24
Reinforcing for column and beam protection — gypsum blocks and hollow terracotta blocks
2019: Sch. 5 (Annex): 11.2
Gypsum blocks and hollow terracotta blocks for the protection of steel columns must have steel-wire or mesh reinforcement in every course and lapped at corners.
S2C25
Reinforcing for column and beam protection — structural concrete and poured gypsum
2019: Sch. 5 (Annex): 11.3
If a steel column or a steel beam is to be protected with structural concrete or poured gypsum, the concrete or gypsum must be reinforced with steel-wire mesh or steel-wire binding placed about 20 mm from its outer surface, and—
- for concrete or gypsum less than 50 mm thick, the steel wire must be—
- at least 3.15 mm in diameter; and
- spaced at not more than 100 mm vertically; or
- for concrete or gypsum not less than 50 mm thick, the steel wire must be either—
- of a diameter and spacing in accordance with (a); or
- at least 5 mm in diameter and spaced at not more than 150 mm vertically.
S2C26
Reinforcing for column and beam protection — gypsum-perlite or gypsum-vermiculite plaster sprayed to contour
2019: Sch. 5 (Annex): 11.4
- “vertical” includes a surface at not more than 10º to the vertical; and
- “horizontal” includes a surface at not more than 10º to the horizontal; and
- “underside” means the underside of any horizontal or non-vertical surface.
Surface to be protected | Reinforcement required if smaller dimension of surface exceeds (mm) | Max spacing of fixings of the mesh to surface (mm) |
---|---|---|
Vertical | 450 | 450 |
Non-vertical | 300 | 300 |
Underside | 300 | 300 |
Upper side of a horizontal surface | Not required | N/A |
Surface to be protected | Reinforcement required if smaller dimensions of surface exceeds (mm) | Max spacing of fixings of the mesh to surface (mm) |
---|---|---|
Vertical | Any size | 450 |
Non-vertical | Any size | 300 |
Undersize | Any size | 300 |
Upper side of a horizontal surface | Not required | N/A |
S2C27
Measurement of thickness of column and beam protection
2019: Sch. 5 (Annex): 12.1
The thickness of the fire protection to steel columns and steel beams (other than fire protection of gypsum-perlite or gypsum-vermiculite plaster sprayed on metal lath or sprayed to contour) is to be measured from the face or edge of the steel, from the face of a splice plate or from the outer part of a rivet or bolt, whichever is the closest to the outside of the fire-protective construction, except that—
- if the thickness of the fire protection is 40 mm or more, rivet heads may be disregarded; and
- if the thickness of the fire protection is 50 mm or more—
- any part of a bolt (other than a high-tensile bolt) may be disregarded; and
- a column splice plate within 900 mm of the floor may encroach upon the fire protection by up to a ¼ of the thickness of the fire protection; and
- the flange of a column or beam may encroach by up to 12 mm upon the thickness of the fire protection at right angles to the web if—
- the column or beam is intended to have an FRL of 240/240/240 or 240/–/–; and
- the flange projects 65 mm or more from the web; and
- the thickness of the edge of the flange (inclusive of any splice plate) is not more than 40 mm.