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Re: 1950's era timber properties

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Title: Re: 1950's era timber properties

There is ongoing research by the Forest Service to evaluate structural properties of what are called "plantation-grown" trees. If you go to the Forest Products Lab website, and search with the word "plantation" or "small diameter" you will get a host of technical papers to review.

The lumber grading agencies continue to evaluate this issue and make adjustments to grading procedures and design properties as necessary. You may recall that in the late 1980's a comprehensive testing program was conducted to evaluate lumber design properties. It was called in-grade testing. Here's a link to more information about that topic:

I cannot be more specific in answer to the question below, because there's just no way to make a blanket statement about "new growth" versus "old growth." As was stated earlier, it also depends on the standard used to evaluate the property.

Rest assured, that the lumber agencies are well-represented on our technical committees and we are updating our standards as necessary to account for any changes to the resource (although according to Bill P., we shouldn't be changing them too often...sorry Bill, but I couldn't resist that little dig there).




John "Buddy" Showalter, P.E.
Director, Technical Media
AF&PA/American Wood Council
1111 19th Street, NW, Suite 800
Washington, DC 20036
P: 202-463-2769
F: 202-463-2791

The American Wood Council (AWC) is the wood products division of the American Forest & Paper Association (AF&PA). AWC develops internationally recognized standards for wood design and construction. Its efforts with building codes and standards, engineering and research, and technology transfer ensure proper application for engineered and traditional wood products.

The guidance provided herein is not a formal interpretation of any AF&PA standard.  Interpretations of AF&PA standards are only available through a formal process outlined in AF&PA's standards development procedures.


----- Original Message -----=20
From: Mlcse(--nospam--at)
To: seaint(--nospam--at)
Sent: Friday, February 03, 2006 6:51 PM
Subject: Re: 1950's era timber properties

I would use the latest NDS values for checking the 8x14, assuming =
DF#1. Methods of testing the properties of wood have changed over the =
years, and design values have changed based upon the testing. Sometimes =
the values go up, sometimes they go down. In some cases, the previous =
testing methods were found to not be accurate, resulting in large =
changes in allowable design values, such as tension values for DF in the =
early 70's.

I would not evaluate a piece of lumber based upon older allowable =
design values given in previous building codes.

Maybe Buddy Showalter can provide additional information, especially =
regarding old growth wood versus new growth wood where trees are =
harvested after a relatively short growing period.
Michael Cochran S.E. SECB

In a message dated 2/3/2006 4:59:00 PM Pacific Standard Time, =
elig(--nospam--at) writes:
Can someone give me a ballpark value for bending stress in an 8x14 =
beam. Assume DF#1. Manufactured in 1950.