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Comment by h2odragon | Hacker News Reader

the long answer to "why is a 2x4 board actually 1.5 inch by 3.5 inch"

considering the inputs, modern lumber is a stunningly consistent and reliable product.

I worked in a retail lumber yard in the mid-1970s and learned to be very patient with crochety old pharts who complained that "a 2x4 used to be a full 2"x4" dagnabbit..." Am now a somewhat crochety old phart myself, and was surprised to find that 1.5" x 2.5" actual (2"x3" nominal) is considered adequate for some studs. Source: https://www.homedepot.com/p/2-in-x-3-in-x-96-in-Select-White...

Am pleased to see that effective hacking has a long history:

> Dimension was fitted into place by the carpenter, more often than not with his hatchet.

> Am now a somewhat crochety old phart myself, and was surprised to find that 1.5" x 2.5" actual (2"x3" nominal) is considered adequate for some studs.

You can frame a wall with 2x3s 16" on center as long as it's not load bearing. That seems pretty reasonable to me, since it doesn't need to do more than hold up the drywall, partition the space, and stand up to people bonking into it.

Mobile homes often use 2x3.

> stunningly consistent

Except now they've found a new way to cheat by putting excessively large radii on the corners of construction grade lumber.

I don't see this as a cost saving - the radius isn't material that would make it onto another piece of lumber, it'd be the waste between rectangles. In addition, keeping a machine tuned and sharp to cut the radius costs money.

I would assume two possible reasons: the radius reduces stress concentration, and facilitating handling and packaging (think splinter fall-off debris, and likelyhood to bind up on a sharp edge)

    > it'd be the waste between rectangles.

It's certainly not being wasted, you can e.g. break it up and use it as material for an OSB, sell it as sawdust etc.

I had intended to point out the minimal amount of this material; I'd be surprised if you could offset the cost of additional milling just to recover it

Pellet fuel.

I thought the radii was a feature because right angles are more difficult to slip into place and tend to splinter more. You're probably right that it's a cost-saving measure though.

The wood in the radii is lost to sawdust. Perhaps they sell this sawdust as a product, but it’s more likely just to make it easier to handle and less likely to get damaged or damage something else.

It’s a “coproduct”, the value of which is roughly inverse to the price of lumber and other finished manufactured end products. It goes into things pulp and paper, pellet stove fuel, cogen plants and if useless for anything else, the “hog” in the basement of the mill. Fun fact: any contamination of chips with plastic or metal makes the value of a load as large as a rail car worth zero, so QC are super anal about keeping it out

2x4 in the rough is 1.5 x 3.5 inch when milled square. Depending on the moisture content when milled and how it is stored/dryed there could be considerable stray from the full, nominal size.

I’m glad my 16 foot ladder isn’t measured this way.

In Fire Walk With Me, there was a deleted scene, now available on The Missing Pieces, involving a confused man who believed he had been shafted out of some wood versus the lumber yard. I had never given it much thought but the scene more or less goes over the why.

Amish mills still sell actual 2”x4”s.

Are those wet and rough cut (unplaned)? https://amishofethridge.com/the-amish-have-great-lumber/

> The 2x4 you purchase at the Amish sawmill is considered wet lumber and is full size but will shrink while drying. The 2x4 from an Amish sawmill will measure a true 2 inch x 4 inch measurement on a tape measure.

They are. Wet lumber is still sadly the norm in Russia for construction work, and 2x4 are still 2x4 there (or rather, 50x100).

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