18 July 2014

Ian and Perry put on the north-south collar ties and then bolted everything together.  After that, they began installing the purlins – 2x10’s that run parallel to the exterior walls between and flush to the tops of the rafters.  The purlins transfer roof load horizontally to the rafters, which transfer the load to the exterior walls, which transfer the load vertically to the house foundation.  As usual, Wikipedia has a good explanation (and pictures) to make this more understandable.  The reason we’re using a huge rafter and purlin system for the roof structure is because the architect-who-should-be-fired didn’t include in the house design any vertically stacked interior walls that could be used for load bearing.  Besides which, Sean needed a challenge…