i have just been asked to replce my friends roof with a 2x4 truss roof. i'm not sure what i should do exactly. whether i should use 2x3's or 2x4's and what pitch i should use. i would like to know if i should consider a weight factor on the walls or should i not? i was thinking about using 2x4's and 1/2" plywood. and composition roof. can anyone tell me an efficient way to do this project? if so it would be greatly appreciated. and thank you.