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Answers to Go with Susan Smith

Sunday, June 9, 2019

Q. Why aren’t 2 by 4 boards really 2 inches by 4 inches?

A. Would you like to read 59 pages on this subject? In 1964, the U.S. Forest service published “History of Yard Lumber Size Standards.”

If you want to read it, we can download a PDF copy, and email it. Or we can pull it up on a library computer.

Oliver J. Curtis included information from this government document in his recent article, “Nominal Versus Actual: A History of the 2x4” which was published in Harvard Design Magazine. It can also be found online.

Here are Curtis’ key points: As many professional builders and home handymen and women know, the 2 by 4 actually measures 1.5 by 3.5 inches.

Before 1870, lumbermen cut and sized trees for individual local carpenters. Final measurements were made on the construction site. As local trees were depleted, the link between local suppliers and local builders was broken.

In the early 1900s, lumber was sold with the purchaser responsible for shipping. It is still sold that way. Lumberman chose thinner, lighter sizes for long trips. The preferred kiln dried wood to control moisture content.

Here are excerpts from Curtis’ article: “This development coincided with the mid-19th-century evolution of building framing — from timber-braced to light-stick balloon and its derivatives — which progressively utilized greater amounts of “small dimension stock,” like 2x4s. And the differences in how lumber was sized, surfaced, and dried became apparent in the lumberyard, where a medley of species in various dimensions claimed to be 2x4s.

“Lumberyards demanded uniformity so that builders could compare cost and quality. As retailers clamored for more regulated measurements and standards, trade associations were formed.

“In April 1919, attendees of the first American Lumber Congress called for size and terminology standardization. However, disagreement about specific considerations persisted for decades.

“Size standards, maximum moisture content, and nomenclature were agreed upon only as recently as 1964. The nominal 2x4 thus became the actual 1.5 by 3.5 inches, imperceptibly, a fraction of an inch at a time. It was a 34 percent reduction in actual volume; as those in the trade would say, it’s ‘selling air.'”

The full article is available online. It does not include a date, but the "Harvard Design Magazine” began publication in 2014. This article was in issue 45.


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