9.0 PURLINS
9.1 CUTTING PURLINS
The location of all the purlins must be known before any
purlins are to be cut. The top purlin is positioned a maximum
of 100mm from the gable ridge (Figure 30) and ends at the
front edge of the gable frame on either side. The end of this
purlin is cut straight to be left flush with the top of the rafter
chamfer (Figure 31).
The lowest purlin shall be a maximum 50mm from the valley
beam (Figure 30) and any intermediate purlins are spaced
evenly on rafters, ensuring maximum recommended deck
end spans are not exceeded. Both the lowest purlin and
intermediate purlin/s will follow the shape of the gazebo end
and therefore purlins will need to be mitred at 67.5 to length
to suit this shape. The highest edge of the gazebo end
purlins will end at the centre of the top face of gazebo hip
rafters. Refer to Figure 31 for further details.
It is recommended the three lowest purlins around
the front of the gable end are set as low as possible on the
hip rafters to eliminate any gap between purlins and gazebo
fascia beams. It is not critical that the level of the lowest
purlins exactly match the purlins adjacent to the valley
beams.
°
Note:
HIP
RAFTER
PERIMETER BEAM
BRACKET
GAZEBO FASCIA
BEAM
12x20 HEX HEAD
SCREWS
>20
>30
>20
29
31
CENTRE LINE
HIP RAFTER
PURLINS
67.5° MITRE
STRAIGHT
CUT
9.2 ATTACHING PURLINS
Where purlins are continuous over rafters they are fixed in
position using 14x95 hex head self drilling screws. If it is
necessary for purlins to be broken over standard gable
frames (ie, purlins continue in the same direction past a join)
a 68mm in-line purlin connector is used.
By drilling pilot holes and screwing through the top of
the purlin before lifting it into position, the process of
screwing into the rafters is made easier. Pilot holes should
also be drilled through rafters at the fixing location.
In the case of purlin joins which occur over a gazebo hip
rafter an angled purlin connector will be required. Fix purlins
together using 12x20 hex head screws. A 14x95 hex head
self drilling screw is fastened through the connector to hold
purlins to the rafter (Figure 32). A gap will be noticed at the
lower edge of the purlin join but this will not be seen after
installation of the purlin intersection cover.
If purlins do not align (ie, lowest gazebo end purlins and
lowest gable purlins) they may be screwed directly into hip
rafters.
Note:
30
MAX
100
mm
50 mm
PURLIN
120
RAFTER
VALLEY
BEAM
RIDGE
(MAX)
13
PURLINS
