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Re: 1950's era timber properties

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Both are correct.  The new testing is designed to do a better job in accounting for size effects in the lumber among other things.
I believe that the difference in the wood itself results from the more efficient methods of tree harvesting which promote faster growth and wider spacing between growth rings.  The primary strength comes from the dense winter part of the growth ring.  The old growth timber which was common over 50 years ago grew in dense forests and  might typically have 50 to 100 rings per inch.  When the old forest is removed due to fire or harvesting, the new trees which may grow from seed, or be planted or, in the case of redwood, grow out of the original root system, have wider sapwood spaces due to fast growth and may have only three to six rings per inch.  This results in less strength, greater shrinkage and less resistance to decay.
Richard Hess, SECB
----- Original Message -----
Sent: Saturday, February 04, 2006 9:55 AM
Subject: Re: 1950's era timber properties

In a message dated 2/4/06 8:47:45 AM, jrgrill(--nospam--at) writes:
That is what I have heard also, that you should check existing structures based on the new stress values.  It's not the wood that has changed, but the methods of testing.

Actually I believe the wood *has* changed in the last half-century, as in not as big, long, straight, etc.