From structural engineer’s BM calcs he derives that I required for roof rafters = 12.65x10^6 mm^4.
He then says I of a 50x150 rafter = 14.06x10^6 mm^4 and to use that. I can agree with that for a 50x150 cross section but the normal dims of a 50x150 rafter is around 44x145 which gives an I of 11.18x10^6 mm^4- less than the 12.65 desired (No longer in touch with the engineer)
He then says I of a 50x150 rafter = 14.06x10^6 mm^4 and to use that. I can agree with that for a 50x150 cross section but the normal dims of a 50x150 rafter is around 44x145 which gives an I of 11.18x10^6 mm^4- less than the 12.65 desired (No longer in touch with the engineer)