Expert: Bruce E. Johnson - 9/30/2008

Question
QUESTION: I need to build a large patio cover.  I am planning 8x8 posts 20ft apart.  I believe an 8x8header will work.  Rafter span is 18 ft with 2x8's on 12" centers.  Rolled roof with shiplap below.  Another section has post spacing 9ft apart but the rafter span is 23ft on 12" centers.  I will use 2x10 in that area for the rafters.  Footings are 24x24x18deep.  Does this sound feasable?

ANSWER: Hi again Kevin, I rechecked the span tables at this website :http://www.awc.org/calculators/span/calc/timbercalcstyle.asp

And depending on your conditions you may be close on in your material and spacing if your roof and ceiling "live load" don't exceed certain limits.  Check it out.
sincerely bruce e johnson..bejohnsonconsulting.com

---------- FOLLOW-UP ----------

QUESTION: Thanks again Bruce for your help!  I haven't been able to find a universal table for the header spans.  That is what I am most concerned about.  Any ideas?

Answer
Hi Kevin, I'm sorry I thought you got both of my email answers. I guess when I sent you the link to the rafter tables my first email got deleted.  Anyways: The header size you suggest 8x8 is a bit puny for a 20' span.  An 8x12 would probably be more like it. Check out this website:
http://newstore.southernpine.com/cgi-bin/newsopine/product?;5;

there is a free header and beam span table you can download..sincerely bruce e johnson..bejohnsonconsulting.com