(57) A spiral staircase is constructed using tread mounting brackets which secure the
treads to the central support column (1) without the need for special mounting collars.
Each tread bracket (2) is clamped to the support column (1) by means of a strap (12)
which passes around the support column (1), the end of the strap engaging grooves
(15,16) in a mounting block (13). The mounting block (13) is provided with one or
more bolts (14) threadedly mounted therein, which engage a back plate (11) of the
mounting bracket (2). Thus, when the bolt or bolts are tightened, the block (13) is
urged away from the back plate (11), the tension in the strap increases, and thus
the bracket (2) is urged towards the column (1).
The baluster (4) is attached to the treads (3) by means of mounting brackets (29)
which are adapted to be slidably mounted in channels or grooves provided in the outer
edges of the treads. Each bracket has a collar which is sliably engageable with the
baluster (4) and means for clamping the collar to the baluster. The baluster may extend
through the collar to belowthe level of the tread (3), and therefore it does not have
to be cut to any precise length.
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