Loren Coe wrote:
i know folks here talk about beam loading, both steel and
wood. i am building several large wall mounted shelves in
a frame home. they are metal L-brackets rated at 500-600lbs
each, topped with 3, 4 or 5 2x4 studs.

there is no spec, or minimum load for these shelves, just want
them to be heavy duty and safe. the brackets vary in width,
16-20 inches. this accomodates between 3 and 5 2x4's on their
side, with some amount of spacing between.

i would rather use 3 & 4, rather than 4 & 5 wood members, if
the wider spacing is no problem. this leads to the question:

with support at 32" intervals, how much load can a 2x4
support on its side?

btw, i am using 5/16"x3" lag bolts to fasten the brackets.

Thanks! --Loren

The species and grade of lumber has to be specified. There is a wide
variance between spruce and douglas fir, for example.