Hi all,
I got turned on to the AF&PA span calculator for joist and rafters recently. It seems to be a most useful tool. A couple of question for those using it or those of you with engineering know how.
What does the term “incised lumber” mean?
Is the “deflection limit” a function of the lumber species, application or type of member, or otherwise listed in the building code tables?
Thanks in advance.
– Rob
Replies
Just guessing on the incised thing -- some lumber gets treated by incising it (putting a bunch of slices in the surface) before pumping in the chemicals. Although the treatment prevents rot and bugs, the cuts have some effect on strength.
Deflection is a matter of how stiff you need your floor to be. The code in most areas will say 1/360 of the span is the allowable deflection for residential floors.
But if you will be laying tile or stone, you need it to be 1/720 or better. And perhaps there are other reasons/products that need stiffer floors.
I won't be laughing at the lies when I'm gone,
And I can't question how or when or why when I'm gone;
I can't live proud enough to die when I'm gone,
So I guess I'll have to do it while I'm here. (Phil Ochs)
Why bother with us dummies when Google and Wiki can tell you all about it, and more?
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"A stripe is just as real as a dadgummed flower."
Gene Davis 1920-1985
Thanks for your thoughtful suggestion, Gene. Didn't think my post would bother many people, but if you found it bothersome, why bother to reply?
Special thanks to the first poster and all the other helpful folks out there on this forum.
- Rob