board thickness in quarters

If I have a 2x4 and measure it out, it's actually only 1.5 thick. When I translate that to quarters it's 6/4 - Or is it ?
If I have a piece of lumber that measures a full 2" thick, that translates as 8/4. True?
If I go to a real lumber yard and ask for lumber at 4/4, what actual thickness will I get?
This all may sound a bit dumb, but I have a money bet riding on the accepted answer from the people here that use the 'quarter' measure more often than I do.
P
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"Quarters" is how big the rough board is *before* they start planing it. So a 2x4 starts off with a 2" by 4" rough blank, then they plane it flat and smooth, resulting in a 1.5" by 3.5" final board.
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What amazes me is that they have to take a half inch off before they get a straight smooth board. I guess its because they standardized on that size, but still, thats a lot of waste.
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They don't start with a 2"x4" chunk of wood anymore.
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wrote:

They don't start with a 2"x4" chunk of wood anymore.
Correct, most mills that kiln dry have a target green size of 1.75" after drying this leaves about 1.625" for planing.
Doug fir mills on the left coast that process all their wood green usually have a target thickness of 1.562"
basilisk
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There's at least ONE area that definitely improves when going metric.
2x4 rough sawn is known as 50x100 (measured in millimetres, one inch%.4mm) and it's really that. If it's a smaller size, then they have to say it's of smaller size (we also have rough sawn 47x100 that is used in different kind of concrete mold supports etc, slightly cheaper).
If you want to have it planed on all sides, it's known then as 45x95 (mm) - it's then really that. Then if it's dimensioned (not necessarily fully planed), it's 48x98mm.
Same rules apply to all sizes, i.e. you can also get fully planed 45x120, 45x145, 45x170, 45x195, 45x45, 95x95 etc.
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jakiiski wrote:

How's that fundamentally any better than standard-sized construction lumber? It's simply a different set of numbers for the same thing.
What primarily (imo) screws up stuff in the US is all the imported crap that's metric instead of US or the "chintzing down" of historical sizes like ply thicknesses by a less-32nd and so on. Hard to imagine such cost-shaving tactics don't go on on the other side of the pond(s), too...???
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On Mon, 14 Dec 2009 14:23:28 -0600, the infamous homer

Erm, you think tubafores are _straight_, Homey? Call this number: 1-800-GimmeAnOptometrist.
P.S: They're cut when green and wet, so cellular shrinkage accounts for some of that loss, too.
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snipped-for-privacy@mts.net wrote:

If it's sold as "8/4" that will be a rough-sawn dimension and if you buy rough sawn that will indeed be the dimension give or take the tolerance of the sawmill and any shrinkage post-mill.
When you buy construction lumber, for example a 2x4, that's also a rough sawn dimension but what you buy is not rough sawn lumber, and there are accepted dimensional standards for construction lumber intended to allow lumber from different suppliers to be interchanged on a job--those standards will have a 2x4 being 1.5x3.5 after being planed to final dimension.

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snipped-for-privacy@mts.net wrote:

Somewhere between 1 and 1 1/4 IME.
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On Dec 14, 2:01pm, snipped-for-privacy@mts.net wrote:

If it's rough sawn hardwood, it's 8/4. Also note that 2x8 dimensional lumber isn't 1-1/2 x 7-1/2, as you might infer from a 2x5, rather 1-1/2 x 7-1/4.

Rough sawn, yes. Once it's planed it'll no longer be 2" thick, though it will still be called 8/4 S2S, or some such.

A 1" thick piece planed down to 3/4", most likely. If its rough sawn it'll be 1" thick.

The best reason going; a bar bet. ;-) We used to call the local library's reference librarian. They loved settling bar bets. ;-)
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On 12/14/2009 02:01 PM, snipped-for-privacy@mts.net wrote:

The "quarter" measurement standard generally only applies to hardwoods (and sometimes softwood decking). The actual thickness of 4/4 lumber depends on whether its rough, S1S, or S2S. (And to a certain extent, the specific case...a quick google search for "4/4 S2S" shows results from 13/16" to 15/16".)
Dimensional softwood construction lumber has its own set of rules and is listed as nominal sizes even though the actual sizes can be up to 3/4" smaller.
Wikipedia has a decent entry:
http://en.wikipedia.org/wiki/Lumber
Chris
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If you are buying rough lumber directly from a mill you can actually specify to have it "skip planed" to any thickness you like for some cents per bf. Keep in mind this is just planing so it won't remove any warp. It just makes it a little less rough. It is nice to have done to something like 7/8" just so you get ride of some of the big rough gouges and bark and to have reasonable similar thickness boards to make processing a little easier. Totally rough material can have a big varience per board or even within a board if it is just straight from the saw.

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snipped-for-privacy@mts.net wrote:

Chris has it right ... hardwood and softwood construction lumber are treated differently, in all dimensions, width, length and thickness, as well as in allowable defects per classification.
The obvious necessity for standardized sizing in construction material makes it a much more reliable "standard" ... IOW, when planning a construction project you really need to be able to count on a tubafour being indeed 1 1/2" x 3 1/2", etc.
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