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6x14 fir, span

codeworks

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Joined
Jun 12, 2011
Messages
579
Location
South Texas
i just got a call from a builder who wants to know if a 6x14 fir (#2) will be good for a 15 feet 3 inch span. it will have 2x8 rafters, 16 o.c, 5/8 ply and standing seam roof. we get no snow, and we don't have the reference material. any help is greatly appreciated. thanks
 
Not enough information. What is the span of the 2 x 8's? Will the beam only carry one end of the rafters? or is it mid span?
 
so 16' wide building with a gable roof, with 2' overhang and 20# live load and 10# dead load? rafters bearing on header? maybe? George Roberts can make it work regardless.
 
Acually, I don't think any overhang will have a negative effect. If the rafters only span 8' (that is 8' from the beam to the ridge, right?) then the beam works in bending by more than double. Its a long span beam so shear won't be an issue. If it supports a brittle surface, like stucco, you could check it for deflection, but seeing as the bending is so over, its not likely a problem, either.
 
If it ain't in span tables it requires engineering. Does George still post here? He can mail you a letter' with engineer's stamp and seal; that states a 2 X 4 will work. Not a good idea to give advice about someting that is not covered by the prescriptive codes.

Uncle Bob
 
If not in the Code itself, by reference it is acceptable to use the NDS from AF&PA.

Not all of the span tables are in the code books... only the most common species and grades.

If I had a copy handy, I'd look it up for you.

If not listed in the NDS, unlikely but possible, then some documentation from an RDP will be needed.
 
if someone came to me in my jurisdiction with this question i would do the simple calculation on my slide rule and proclaim that the beam is adequate by alot. but that is just me. why send them to an engineer that would charge bukoo bucks for a simple beam calc?
 
codeworks said:
i just got a call from a builder who wants to know if a 6x14 fir (#2) will be good for a 15 feet 3 inch span. it will have 2x8 rafters, 16 o.c, 5/8 ply and standing seam roof. we get no snow, and we don't have the reference material. any help is greatly appreciated. thanks
Tell him to ask his registered design professional.

But if you want to play with it, we need to know the specific type of wood
 
On the awc.org website you can download the WCDD manual, there is a good set of instructions near the beginning. It would give an answer as acceptable as using a table in an LVL book.
 
Thanks Gary, WSDD, I scrambled it up there somewhere... Wood Structural Design Data;

Wood Structural Design Data Revisions

Just from a quick look, assuming dougfir in #2 heavy timber it would be good for around 450 PLF or ~7000 lbs uniformly distributed.
 
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