Timber sizes

American lumber standards has changed the dressed sizes of timbers larger 7 inches to be 3/4's inch smaller than nominal size.
8x8's that used to be dressed to 7.5x7.5 inches will now be 7.25x7.25.
Just passing this along.
http://www.alsc.org/greenbook%20collection/ps20.pdf
basilisk
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basilisk wrote:

Is this only timbers and not dimension lumber?
Give it a few years and you're going to have to order a 7 x 7 to get a 6x6.
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for the change is that the density of timber isn't what it used to be and shrinkage in rough lumber was such that it made the old size hard to dress completly out.
This only applied to timbers larger than 7 inches so the 6x6 size won't change, at least not anytime soon.
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On 2/26/10 11:16 AM, Mark & Juanita wrote:

I don't know how old that is, but the 2x's that I get, 8" and above, have been -3/4" for as long as I can remember.
So yeah, maybe it's the square stuff.
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have been dressed 3/4 inch under nominal since the late 1960's I believe.
basilisk
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Just bought some 1 X 6 Ponderosa Pine and it is 5 1/4.
Jim in Milwaukee
basilisk wrote:

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On 2/26/10 12:26 PM, basilisk wrote:

About 15 years ago (wow, has it been that long), when I built our first home, I used a local sawmill for the wood for our Sharn (too big for a shed, too small for a barn).
It was all green white pine and the joists were cut to nominal sizes... still 1.5", but the 8's were 8" and the 10's were 10". It was strange, but fun to see that.
Two things I distinctly remember... 1) they were straight as an arrow and a joy to work with. b) IIRC, they shrank less than a 1/4" in the depth.
--

-MIKE-

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On Fri, 26 Feb 2010 09:17:02 -0600, the infamous "basilisk"

That document is PS 20-05, as in 2005 printing date. There is no change _today_ to the (diminishing) size of dimensional lumber as we know it.
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On 02/27/2010 10:34 PM, Larry Jaques wrote:

under ALSC are just now pushing this into the mills.
I have no idea why it has taken 5 years to reach the mill level, but I will give Timber Products Inspection(agency I work under) a call Monday and try to find out what the process is.
I "think" these changes come from NIST and are passed to ALSC and then to the grading agencies for comments and gripes all along the chain of production and regulation, quasi govt. beauracracy at it finest.
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On Sun, 28 Feb 2010 11:22:12 -0600, the infamous basilisk

Where are you based, b?

Two things bother me. First, I haven't seen any recent changes in lumber sizing. Second, you say grading agencies are just now pushing it into the mills, but the old document is produced only to reflect what's hitting the streets from the mills under voluntary agreement.
I'm missing something, so please tell me what you're saying here. I first read it as a caveat to us that things were about to change, but I then checked the copyright date.
Me's puzzled.
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--Oscar Wilde (1854-1900)
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On 02/28/2010 06:37 PM, Larry Jaques wrote:

at a local lumber company, that produces anything southern yellow pine lumber and various hardwood products.

Where to start, I think I've taken for granted everyone knowing some nomenclature that I shouldn't have.
2x, 3x and 4x stress rated lumber is graded under a set of rules known as dimension lumber and these rules are written by regional grading agencies to account for strenght differences in species. In the south the rules are written by Southern Pine Inspection Bureau, there are other grading agencies in the south but they have to use SPIB's rules. (There are 7 rule writing agencies in US and Canada) The rules nationwide are under the National Grading rules which specify sizes and stress ratings for standard grades. This allows construction designs to be portable from one region to another. There haven't been any changes in the sizes or defect specifications for dimension lumber.
Timbers are classed as any product bigger than a 5x5, so even a 4x12 isn't considered a timber as far as the grading rules are concerned.
The smallest commonly available timber that the size change will apply to will be an 8x8, in the past the dressed size was 7.5x7.5 inches, soon it will be 7.25x7.25 inches, and will apply to any timber at least 7 inches thick and wider than 7 inches.
Many years ago(too lazy to look up dates) the grading agencies were formed to level the playing field between mills and to standardize sizes, later the federal gov't stepped in and told the industry to either police yourself or we will, so by voluntary agreement American Lumber Standards was formed, their primary job is to inspect mills as well as end users to insure that the grading agencies are playing nice with each other and to insure the mills are properly inspected.
The mill that I work at(and most mills) are subject to grading agency inspections monthly or more often depending on production level of the mill, and ALSC has surprise inspections at any time, although I am subject to ALSC inspections, they are primarily checking to see if the grading agency reports match their findings on inspection.
I don't know where the changes originated, changes like this can originate from disgruntled mills at the bottom or NIST at the top, or anywhere inbetween(for my own curiousity, I hope to find out). As far as the date of ps20 is concerned, most likely after a change was agreed to, ALSC give the industry nationwide a migration and compliance date, I was notified by my grading agency on 2/19 about the "upcoming" changes.
To make matters more complex than they already are the standards for size and stress rating only apply to grademarked lumber and even then if a mill or customer should want to sell or buy an alternate size all that has to be done is include the sizing on the grademark and it becomes legal. A good example of this is 5/4 decking, it is common for it to be ran as 5.5 wide or 5.375, only the 5.375 size would have to have the size on the stamp as the 5.5 is standard width.
basilisk
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