Purlins

In framed trusses spaced not over 5 ft. centre to centre the purlins shall be not less than 2 in. x 4 in. set on edge and space 30 in. from centre to centre. If trusses are spaced over 5 ft. centre but not over 8 ft. purlins shall be 2 in. x 6 in. spaced at 30 in. from centre to centre. If trusses or common rafters are spaced at distances not exceeding 30 in. from centre to centre, batten purlins 1 in. x 4 Public Health 19 in. may be used - if spaced at centres not exceeding 2 ft. and securely nailed to rafters.