yeah,,,the purlins on the osb is overkill,.,,,but since it is a windy area, i felt better about the screws in the purlin compared to the osb. if i was doing this again i would have used plywood for the roof and attached directly. and yes,,i have done all the work myself with some help from friends and family. the only thing i did not do was the concrete placement. its been a hell of alot of work.!