FAQs about using framing tables for wood construction: joist & beam spans & sizes.
This article series gives recommended or allowable joist & beam spans and explains typical spans for joists, beams, and roofs, floors, giving both standard span tables and a quick "rule of thumb" that works pretty well.
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These questions & answers v were posted originally at FRAMING TABLES, SPANS - be sure to consult the tables and rules of thumb given there.
On 2018-06-23 by (mod) - rule of thumb for using 2x6's
Thanks for the thank you Red. We work hard to provide authoritative data so we're grateful when a reader finds it useful.
In Steve Bliss’ tables above Table 4-7 gives beam sizes (click to enlarge) and Table 4-8 gives joist spans.
A typical 2x6 SYP (the most common you’ll find at a Home Depot store or Lowes)
according to the table in DECK FRAMING TABLES, SPANS when spaced 16” o.c. can span 9’9”
Our “rule of thumb” discussed earlier on this page and applied to a 2x6 would have given
(6-2)x2 = 8 ft. allowable span,
which would have been within the actual joist span table and would have been “safe”.
Questions, content criticism, content contributions, photos (of your deck) are entirely welcome.
- Editor
On 2017-06-28 by Petrosorr
I have a situation I'm looking for advice on. I own a 1928 house in Seattle that was constructed 20' wide with a 6x6 beam spanning the joists in the center of the basement.
The beam sits on 6' tall 6x6 posts (it's a low ceiling), staggered 8' OC.
A chimney at one end of the house interrupts the beam, with the final section spanning 8' beneath the living room.
I would like to replace this final 8' span with two 6x6 beams on either side of the chimney. Since the chimney is two feet back from where the current post supports the beam, the two new beams would be spanning 10'-6" instead of 8'.
I can't very well use a larger beam as the head height is already quite low. I've read around that 6x6 Doug Fir isn't advisable as a beam, but the current beam has been in place for 90 years and I would imagine two of them would split the weight.
Can anyone advise for or against two 6x6 beams spanning 10'-6"?
On 2016-12-03 by Max McKnight
Using 2x6 joist, do they need to be supported on 8'3". Maybe I didn't,read correctly the chart. Tanks
On 2016-07- by Ted
looking for joist span info for hem fir used in a tree house
...
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