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Posted by RicodJour on January 11, 2008, 5:19 pm
>
> > I have a 14-foot by 6-foot almost flat porch roof, and the porch roof is
> > held up by one column one each of the two front corners. Right now, across
> > the front there are two 2"x6" beams sistered together.
>
> > Can anyone tell me if that is considered sufficient under current building
> > codes, or where I can find some kind of info or load span table saying what
> > is needed for this situation?
>
> > I am in New Jersey.
>
> I just ran a quick calc with some large assumptions. I figured Hem-
> Fir, No. 1 grade equivalent (older houses were generally built with
> better wood), 70 PSF which is definitely higher than you'd experience
> (figured 30 PSF live load as it's almost a floor, 10 PSF dead load,
> and 30 PSF snow load for a 2 month duration), and it passed in all
> respects. The deflection was a bit high - almost an inch - but since
> it's a porch it's unlikely that that would present problems ( it's
> still standing, right?). If the porch roof is used as a deck, the
> live load would be higher, but it's unlikely that you're congregating
> on the porch roof while there's two feet of snow or more on it.
>
> For your own edification and reference purposes, the Canadian Wood
> Council web site has a nifty online span calculator. It's under the
> Design Tools heading, IIRC.
>
> R
Whoops! Scratch that! My blood sugar must be running low - the beam
fails and has more than a _three_ inch deflection with the loads I
listed above. I also just checked the Canadian Wood Council's site,
and they've changed things around since I was there last. You'd have
to download one of of their demo packages to calculate beams -
probably not worth it.
Here's an online calculator for a simply loaded beam:
http://www.forestryforum.com/members/donp/beamclcNDS2.htm
It's a bit more complicated. That one shows 3 @ 2x10 is required,
like EXT mentioned, which is adequate for a floor which has more
stringent deflection criteria.
What are you trying to do? If you're looking to stiffen the beam you
could sister on a 2x10 on either side and bolt them together, or you
could bolt on some steel plate or channel.
Sorry for the hit-send-before-thinking post.
R
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