(57) A building construction comprising a first rafter (13) substantially parallel with
a gable end (11) and defining therewith an end bay, a second rafter (13) parallel
to the first rafter and defining therewith an intermediate bay, a third rafter (13)
parallel to the second rafter and defining therewith a further intermediate bay, and
a purlin (14) spanning said bays and supported on the gable end and each of said rafters,
said purlin (14) being formed from n cold rolled sections (14a, 14b) of predetermined length, and a first purlin section (14a) spanning said end bay and being joined to a second purlin section (14b) over said first rafter (13) by an overlapped joint (14c), the end of the second section remote from the first section being joined to a third
pulin section (14b) above a respective rafter by a sleeved joint (14d), the n -2th section (14b) being connected to the n -1th section (14b) by a sleeved joint (14d) above a respective rafter, and the nth section (14a), being an end bay section at the end of the purlin remote from the first mentioned
end bay section, being connected to the n -1th section (14b) by an overlapped joint (14c) above the rafter adjacent the second gable end, said first and nth sections (14a) of the purlin being formed from a material of heavier gauge than the material of
at least some of the intermediate sections (14b).
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