why is a 2 x 4 lumber not 4 inches wide?

Question

why dont they call them 1 1/2 x 3 1/2 thats the size they are. 2x6 are the same way how can i build something that says use a 2 x 4 when they are all a way smaller

Answer 1

As you and DAVID point out there are variations in sizes. What I'm buying lately ranges in the fractions from 3/8 to 3/4. He is also correct about getting more lumber from the mill stock, and a change of standards. Kinda like the purchasing value versus the FACE value of a DOLLAR.

Lumber also used to carry a level of quality not evident today,,,sadly. No real offense meant to Big Box stores but at some point those 2x4 studs, etc, that were so warped, so green, so full of knots, that render them useless, will end up in a fire or chipper.

As a society and species I think we accept too much of too little as OK, though I suspect as in all things, my one voice won't make much difference.

Steven Wolf

Answer 2

The answer is mentioned above, but not all in one nice, concise, causal package ... so I'll add my 2 cents:

2x4's used to be 2" x 4" - however, they were rough-sawn at that dimension and very difficult to handle without getting splinters, catching, etc. Both builders and DIY'ers, preferred planed lumber - but wood is lost in that planning process. (Please note that 'planed' is not the same as 'S4S' or "sanded 4 sides" lumber, which has a finer surface yet.)

It's not really a matter of greed or anything else. The mills are simply giving the people what they want, lumber that's easier to handle and move without catching or causing cuts and scrapes.

If you live in a lumbering area near a mill, you can still get rough-sawn construction lumber. Most furniture wood (oak, walnut, cherry, etc. is usually still bought rough sawn - except at big box home centers. The craftsmen themselves do the planing in their shops.

The link below has a more concise explanation.

Answer 3

Back in the day a 2x4 was actually 2" x 4", it is a building standard now that if a project asks for 2x4 lumber that it will be 1-1/2" x 3-1/2", same goes for other dimensional lumber.

Answer 4

The thickness of hardwood lumber is measured in quarters of an inch, such as 4/4 (four-quarters or 1"). This is the thickness before surfacing and is what you would use to calculate the board feet. This is also the thickness that you would pay for, even though the planed thickness may be only 3/4" of an inch thick. The chart below shows the typical thickness before and after planning for hardwood lumber.

4/4 = 1" 13/16" 3/4"
5/4 = 1 1/4" 1 1/16" 1 13/32"
6/4 = 1 1/2" 1 1/4" 1 13/32"
8/4 = 2" 1 3/4" 1 1/2"

the difference from what I understand is you are thinking in inches and feet...and lumbar is measured in 'board feet' which is different.

Answer 5

In our grandfather's time, lumber was cut 2"x4" and it was sold rough, which means that you could see the saw marks and your hands suffered splinters. At that time, the measurements were also pretty rough, so 2x4's ranged from 3 3/4" to 4 1/4", sometimes within the same piece of wood.

Then came modern efficiency, accuracy, economy and facility. The 2x4 became 2"x4" before cutting, so it shrank by the thickness of the saw blade. And, people wanted a smoother finish to make it easier to handle and apply gypsum board and the planing process shrunk the finished product to what we see today. Modern machines are also adjusted more precisely so that lumber is more uniform.

In short, lumber is sold by the board-foot before processing (cutting, planing, sanding, etc.).

Answer 6

A lot of good answers, but not entirely lumber company greed (although I'm sure that had a lot to do w/ it). They started cutting back on the size of studs when drywall became commonplace. House plans did not account for the thickness of the drywall, and people were running into trouble with what we in the industry call wall creep. Doorways, windows, all were left to suffer because space had to be made up somewhere. Instead of redrawing all existing house plans, and changing the way all house plans would be drawn, they started making studs 1/2" leaner to allow for the mounting of 1/2" of drywall.

Answer 7

2x4 is called the nominal size. It is the rough size before finishing.

In theory that is the size they rough cut it at the saw mill. Once it is kiln dried it shrinks down a bit and they dress it [remove the saw marks] to the final size in a machine more or less like a four sided planer

Tutto is correct, in the old days they framed with rough lumber, as time passed they began to finish it. Not always to any standard. For a time they must have make the 1 5/8 x 3 5/8 because I have seen them.

Answer 8

Funny that this is in the math section. A 2x4 is 2 inches by 4 inches before being planed to make all the edges straight

Answer 9

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Answer 10

rough cut they are 2x4 finish product is 3 1/2 x 4 1/2