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328 Barry’s Advanced Construction of Buildings
Steel column
Steel mesh
reinforcement
to concrete
Solid concrete
cover minimum
thickness 50 mm
for 4 hour and
25 mm for up to
2 hour protection
Figure 5.52 Concrete fire protection.
in Figure 5.52. The disadvantages of a concrete casing to steelwork are its mass, which
considerably increases the deadweight of the frame, and the cost of on-site labour and
materials in the formwork and falsework necessary to form and support the wet concrete.
Brick casings to steelwork may be used where brickwork cladding or brick division or
compartment walls are a permanent part of the building, or where a brick casing is used
for appearance’s sake to match surrounding fairface brick. A brick casing is an expensive,
labour-intensive operation in the necessary cutting and bonding of brick around columns.
Blockwork may be used as an economic means of casing columns, particularly where
blockwork divisions or walls are built up to structural steelwork. The labour in cutting and
bonding these larger units is considerably less than with bricks. The blocks encasing steelwork
are reinforced in every horizontal joint with steel mesh or expanded metal lath.
5.7 Floor and roof construction
Functional requirements
The functional requirements of floors and roofs are:
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Streng.th and stability
Resistance to weather
Durability and freedom from maintenance
Fire safety
Resistance to the passage of heat
Resistance to the passage of sound