California 18' garage door question
California 18' garage door question
(OP)
I am in the middle of a disagreement with my structural engineer. For a 18 feet by 8.5 feet door opening, my structural engineer instructs me to frame it just like a 2 feet wide window except a bigger header on double studs. I think it's wrong, but I don't know what to show him. Can anyone point me anything to prove he is wrong?
Thanks.
Thanks.






RE: California 18' garage door question
With the very information you have provided, I can give no definitive answers here, and there are many reasons why he is probably correct.
Mike McCann
MMC Engineering
RE: California 18' garage door question
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RE: California 18' garage door question
RE: California 18' garage door question
You should not have to educate someone working for you.
It very well might work per the numbers. If so, you should be satisfied.
RE: California 18' garage door question
RE: California 18' garage door question
With that said I would definitely but 2 jack studs beneath the header. With 2 jack studs you would be capable of supporting a reaction say ~4,000 lbs (off the top of my head)
I'd be most concerned with the king studs for out of plane loads on such a large opening.
RE: California 18' garage door question
Isn't that data dependent on average humidity? In very dry climates (Southwest US), shrinkage would be higher?
RE: California 18' garage door question
a free download from http://www.fpl.fs.fed.us/products/publications/sev...
"Longitudinal Shrinkage
Longitudinal shrinkage of wood (shrinkage parallel to the
grain) is generally quite small. Average values for shrinkage
from green to ovendry are between 0.1% and 0.2% for most
species of wood. However, certain types of wood exhibit excessive
longitudinal shrinkage, and these should be avoided
in uses where longitudinal stability is important. Reaction
wood, whether compression wood in softwoods or tension
wood in hardwoods, tends to shrink excessively parallel
to the grain. Wood from near the center of trees (juvenile
wood) of some species also shrinks excessively lengthwise.
Reaction wood and juvenile wood can shrink 2% from green
to ovendry. Wood with cross grain exhibits increased shrinkage
along the longitudinal axis of the piece.
Reaction wood exhibiting excessive longitudinal shrinkage
can occur in the same board with normal wood. The
presence of this type of wood, as well as cross grain, can
cause serious warping, such as bow, crook, or twist, and
cross breaks can develop in the zones of high shrinkage."
Garth Dreger PE - AZ Phoenix area
As EOR's we should take the responsibility to design our structures to support the components we allow in our design per that industry standards.
RE: California 18' garage door question
I could be wrong but I seem to remember that wood shrinks tangentially somewhere in the neighborhood of 10x the amount it shrinks in length. I'm sure Garth's reference would have better info.
RE: California 18' garage door question
RE: California 18' garage door question
John Southard, M.S., P.E.
http://www.pdhlibrary.com/
RE: California 18' garage door question