i’m hanging some relatively light loads (canoe) from an i joist rafter (16′ clear span, 9-1/2″ bci 6000) in my little outbuilding. according to span tables nothing is overloaded (yet), but i reinforced the rafter anyway, per detail A in the following APA document…

https://www.woodworks.org/wp-content/uploads/Anthony_Construction_Practices.pdf

i would like to hang more stuff, but i’m hesitant. i understand that adding material to an i joist primarily stiffens it, but it will also increase its load-bearing capacity to some degree. the question for anyone who’s got some math and stuff: how can the increased stiffness and strength be quantified? it would be nice to have a general idea of what the reinforced rafter is likely to do.

thanks – ian.