wood framing common practice

huangyhg

wood framing common practice
my boss always tell me to use at least double 2xs or lvls when i have a beam.  his reason was because you want more room nailing the floor joist/roof rafter connectors.  so theres many time when i calculate beams i only need 1 lvl and he told me to put 2 instead.  do you guys do this also?
he also tell me to use at least 3 2xs or lvls on 2x6 stud walls for headers because it will match the wall thickness. by doing this, the framer doesnt need to fill the gap that much.  so he rather uses (3)-1 3/4x9 1/2 lvls instead of (2)-1 3/4x11 7/8s lvl or (2)-1 3/4x9 1/2 lvls
i agree with using (2) for 2x4 walls and (3) for 2x6 walls.
i have noticed in home construction, some framers using (2) in 2x6 walls with no blocking between to match the width of the wall. i do not agree with this approach. everybody seems to be trying to cut corners.
i have grown up in construction and i was under the understanding that the double part of a beam and/or header was for lateral strength.
i see builders using 2 in a 2x6 wall, flush to the outside of studs with insulation in the void created.
i've seen a single 2x beam in a 2x4 wall used fairly often by a fairly large builder here locally.  it's set flush to the outside and insulation placed on the interior.  i don't necessarily agree with this, but they do it all the time.  
i agree with your boss.
how about beams not in the wall?  do you always put double?
mostly i've seen 2 ply beams used.  i have seen single ply paralam's used but usually they are 3.5" wide.  
if you have a framing connector tying into a beam, you often need the extra thickness for nail penetration.  simpson's catalogue will tell you the minimum header thickness required for their connectors.   
although it seems really strange, your boss is doing what is best (ie: following best practice).  take it from someone who's none too many years from his first designs: once you're out on site a bit and can see what's happening, you'll realise the value.
also, there is a very simple reality when it comes to timber:  our design values, timber properties, etc. are all based on the 5th pecentile value.  that means, in effect, that for every twenty single ply beams you specify, one will be understrength.  doubling up virtually guarentees that this won't occur, as the other 19 members are likely to be stronger than the 5th percentile, so your combined member is sweet.
i've learnt a very simple rule (and something canadian engineers are "taught" at the end of their undergrad degree) to be very true.  i don't know what i'm doing, and i'm here to learn.  once i've done it five times, then i start to (gently) second guess more senior engineers.  this is always done with a great deal of respect, in an air of comeraderie, and with the (often stated) goal of prompting more knowledge out so that i can better my work and designs...
good luck, and keep posting,
this forum was invaluable for me starting out,
ys
b.eng (carleton)
working in new zealand, thinking of my snow covered home...