On Wed, 18 Jul 2012 21:14:38 +0000 (UTC), HerHusband
wrote:

I can't say for sure without more info but I suspect
your [40psf] Live Load is too high.

I wasn't sure where the OP was located, so I erred on the side of heavier
snow loads. I've always used 30psf for live load calculations here in my
area. In any case, I calculated it with the 30 psf and still came up with
about the same size beam.

When we built our house, I asked the truss company to design for 50 psf
live loads, since we occasionally get heavy snow in the winter. Ironically,
the only change this required in the trusses was slightly larger metal
connecting plates. Kind of surprised me.

Anthony Watson
www.anthonywatson.us
www.mountain-software.com


grin. People often overlook the connections and seem to just worry
about the beams / columns. Usually we try to make the connections
stronger than the beam because if it fails at the connection, it can
be sudden vs. the beam, usually bends before failing allowing people
to get off. I'm a retired structural engineer so I speak from
experience. Most of my experience is in steel / concrete but for a
short part of my career I did wood (homes). Be careful tho when
using your liveload because if you take full snowload with a full
liveload (think what liveload is meant to include here), that's not
likely in a real world sense. Sometimes in engineering we have to
make educated guesses what we think the real loads will be over the
life of a structure. Of course we would like to over design but
depending on the structure, that can be too costly and most clients
don't like that. Last, I commend you for thinking about loads when
building your home... most people take this for granted.