Workshop: Roof Frame Practical

Today we got rained off site, so started on our roofing practical in the workshop which was to make a roof frame like the one on the Unitec building (but on a smaller scale).  We split into groups and were each given a different pitch.  

I was with Ben, Erin & Periri & our pitch was 42degrees.  Using this information we were able to calculate the length of the rafter and rise.  We did a mock plan on a piece of paper & based our run on the length of the workshop table.  We did this plan so that we could get the angles for the two different area's 

on the roof that would require them (so we could figure out their pitch).  

Once done, we started cutting out 6 rafters to length with the angle cuts at the end (one to sit flush against table surface (which was acting as our top plate) and the other to sit flush against the ridge).

The ridge board was then cut (which was the length of the table with 200mm added to each end to account for the overhang).  On the ridge, a running measurement was done to figure out where the rafters would sit along it.  This was done by taking off the 200mm for the overhang, instepping this by 150mm then every 400cr.  These same markings were also done along the span of the table (starting from the 150mm instep as the 200mm overhang is not present along this length).  

Once all the markings were done, the rafters were temporarily tacked down to the table, and then the ridge was inserted down the middle of these rafters.  The rafters had to be flush with the bottom of the ridge board and the markings previously scribed.  A level was then used to make sure that the ridge board was centered by runnng vertically at the rise & also along the top of the ridge board as well.  Once correct the rafters were nailed in to the ridge board.  

We then started prepping the gable end rafters to sit lower to support the outriggers & fly rafter.

This was done by scribbing out on the table the thickness of the rafter (as this is the new line that it must sit on the table.  The length from mid way through the thickness of the ridge, down to new marking on the table is then taken (as this is the length of the gable end rafter.  The same angles as the other rafters were then cut with an edge cut taken so that they both join under the ridge and are flush with the bottom of the ridge.  These were then also attached as the other ridges.