283757893275

428 Barry’s Advanced Construction of Buildings
of steel alloys containing chromium and other elements. The type of stainless steel commonly
used for structural fixings is austenitic stainless steel.
Loadbearing fixings
Corrosion-resistant metal angles or corbel plates are used to carry the weight of the stone
facing. These fixings are bolted to, built into or cramped to slots in the background wall
or structure. The loadbearing fixings provide support at each floor level at not more than
3 m. The fixings bridge the cavity to provide support at the bottom or close to the bottom
of slabs, with two fixings being used to each slab. Loadbearing fixings take the form of
stainless steel angles or corbel plates that fit into slots cut in the bottom edge or into
slots cut in the lower part of the back of slabs at each floor level or at vertical intervals of
about 3 m.
Common practice is to support each facing slab on two supports, with the angle or corbel
supports fixed centrally on vertical joints between slabs so that each supports two slabs.
Angle and corbel plates should be at least 75 mm wide. At vertical movement joints two
supports are used, one on each side of the joint, to the lower edge or lower part of the two
stone slabs on each side of the joint. These separate supports should be at least 50 mm wide.
Angle loadbearing fixings are bolted to the in situ concrete or brick background, with
expanding bolts. Holes are drilled in the background into which the bolts make a tight fit
so that, as the bolt is tightened, its end expands to make a secure fixing. Angles may be
fixed to provide support to the bottom edge of slabs, with the supporting flange of the angle
fitting into slots in the bottom edge of adjacent slabs so that a narrow horizontal joint
between slabs may be maintained. Angle support to the thicker sedimentary stones is often
made to grooves cut in the backs of adjacent stones, some little distance above the lower
edge, into which the flange of the angle fits. This fixing is chosen where the edges of these
laminated stones might spall where the lower edges were cut. Figure 7.9 is an illustration
of loadbearing angle support fixings.
Corbel plate loadbearing fixings may be used as an alternative to angle supports, particularly
for the thinner stones such as granite. Flat or fishtail corbel plates are from 6 to 16 mm
thick, depending on the size of slab to be supported, 75 or 50 mm wide and from 125 mm
long. The purpose of the fishtail end is to provide a more secure bond to the cement grout
in which the corbel plate is set. A pocket is made in the concrete or brick background by
drilling holes and chiselling to form a neat pocket into which the corbel plate is set in dry,
rapid-hardening cement and sand, which is hammered in around the corbel. The one part
cement to one part sand grout is left for at least 48 hours to harden. Corbel plate supports
are usually fixed to provide support by fitting into slots cut in the back of adjacent stones
some little distance above the lower edge of slabs, as illustrated in Figure 7.10.
Two corbel plates are used to give support to the stone facing at each floor level or not
more than 3 m. The thickness of the plates and the depth of their bed into the background
have to be sufficient to give support for all the stone slabs between floors. A common
alternative to flat corbel plates is to form the protruding ends of corbels, which fit into slots
in the back of stones, to slope up at an angle of 158° to the horizontal. The upward slope
provides a more positive seating for stones and to an extent serves to restrain and align the
stones. The setting into the background of the corbel plates and the cutting of the slots in
the back of the stones require a degree of skill to achieve both an intimate fit of stones to