Replies

1. 
   Mark_T. | May 12, 2000 06:27pm | #1

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   Ceiling joists, floor joists, or what? What kind of wood? What grade? (I know you wanted to use #1 for all your framing). I'm gonna have to charge you extra if I gotta read your mind.

   Here is some links I found in the archives:

   Span Chart #1

   detailed span chart

1. 
   Jerry_S. | May 14, 2000 10:21pm | #2

   *Go to the Southernpine Council's web site, http://www.southernpine.com. They have a complete set of joist span tables.

2. 
   Guest_ | May 14, 2000 10:58pm | #3

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   A pretty safe rule of thumb is one foot of span for inch of depth of joist. 2X8 easily spans 8', 2x10 spans 10' for example. Those are conservative spans, but they're pretty well accepted. You might find it cheaper to go to 2X6 joists and add another beam under them too. I use 2X6 mud sill for deck joists all the time like that because they are so cheap. All right all you purists, fire away at that one.

1. 
   Guest_ | May 15, 2000 05:09am | #4

   *Assuming that you are talking about floors (?), with what deflection criteria (thats the L/360, L/240 number in the span chart referenced above, which may be governed by your building code)? How much 'bounce' are you willing to tolerate, etc. If you follow the conservative rule of thumb above you won't have much, but if you stretch 2 x 8 floor joists beyond 16' or so, depending to some degree on lumber grade, you'll have plenty. How does 5/8" - 3/4" of deflection sound to you?

1. 
   Guest_ | May 15, 2000 02:31pm | #5

   *But, too stiff a floor can be a problem too. There's alot written about floors so stiff they vibrate instead of just bounce and floors so stiff that they are actually uncomfortable to walk on.

1. 
   Guest_ | May 15, 2000 04:20pm | #6

   *And there is a reason why sometimes it's good that a FAQ gets asked again. That is surely the first mention on this site that a floor can be too stiff.Rich Beckman

1. 
   Guest_ | May 15, 2000 05:56pm | #7

   *"Too Stiff"?Tell me more on this please.

2. 
   Guest_ | May 17, 2000 01:51am | #8

   *I don't know anything about this other than a few articles I've read. Long spans using oversized I-joists are what I've read about. The floor can be so stiff that instead of just deflecting, it vibrates like the skin of a drum.

3. 
   Guest_ | May 17, 2000 02:13am | #9

   *... But it's a porch, and I can't remember the last time I walked out on a porch and thought - 'wow that's a stiff one.' Usually the ones you remember are more like 'shakytown'.

3. 
   Jeff_Zibrat | May 17, 2000 02:14am | #10

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   Where can I find maximum spans for 2x8 joists for porch ? ie: How long can you let 16"o.c. 2x8's run from header to header?