Annexure To Table 1
1. Mortar, plaster and plaster reinforcement
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.
Gypsum blocks must be laid in gypsum-sand mortar or lime mortar.
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.
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.
Plaster prescribed in Table 1 must consist of—
cement and sand or cement, lime and sand; and
may be finished with gypsum, gypsum-sand, gypsum-perlite or gypsum-vermiculite plaster or with lime putty.
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, and
with the reinforcement must be securely fixed at a distance from the face of the wall of not less than 1/3 of the total thickness of the plaster.
2. Ashlar stone masonry
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.
3. Dimensions of masonry
The thicknesses of masonry of calcium-silicate, concrete and fired clay are calculated as follows:
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.
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.
The equivalent thickness of a masonry unit is calculated by dividing the net volume by the area of one vertical face.
4. * * * * *
This clause has been deliberately left blank.
5. Height-to-thickness ratio of certain walls
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—
6. Increase in thickness by plastering
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 Table 1 (but not for the purposes of Annexure Clause 5) may be increased by the thickness of the plaster on one side.
Where Table 1 indicates that column-protection is to be plastered, the tabulated thicknesses are those of the principal material. They do not include the thickness of plaster which must be additional to the listed thickness of the material to which it is applied.
7. Gypsum-perlite or Gypsum-vermiculite plaster on metal lath
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.
For the fire protection of steel columns with gypsum-perlite or gypsum-vermiculite on metal lath—
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, andthe thickness of the plaster must be measured from the back of the lath.
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.
8. Exposure of columns and beans
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.
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.
9. Filling of column spaces
The spaces between the fire-protective material and the steel (and any re-entrant parts of the column itself) must be filled solid with a fire-protective material like concrete, gypsum or grout.
The insides of hollow sections, including pipes, need not be filled.
10. Hollow terracotta blocks
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%
11. Reinforcement for column and beam protection
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.
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.
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.
If a steel column or steel beam is protected with either gypsum-perlite or gypsum-vermiculite plaster sprayed to contour and the construction falls within the limits of Table 11.4, the plaster must be reinforced with—
The reinforcement must be placed at a distance from the face of the plaster of at least 1/3 of the thickness of the plaster and must be securely fixed to the column or beam at intervals of not more than the relevant listing in Table 11.4.
For the purposes of Table 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.
Table 11.4 Reinforcement of gypsum-perlite or gypsum-vermiculite plaster sprayed to contour
|Surface to be protected
|Reinforcement required if smaller dimension of surface exceeds (mm)
|Max spacing of fixings of the mesh to surface (mm)
|Vertical members with H or I cross-section:
|Upper side of a horizontal surface—
|Vertical members with other shapes:
|Upper side of a horizontal surface—
12. Thickness of column and beam protection
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 1/4 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.