When Did a 2x4 Stop Being a 2x4?

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For those who don’t know, the terms for some of the most common materials used in construction are actually misnomers. Did you know that a 2x4 isn’t actually 2 inches by 4 inches? In reality, it measures 1-1/2” x 3-1/2”. And that's not all; the same discrepancy applies to other lumber sizes. A 2x6, for instance, is actually 1-1/2” x 5-1/2”, and the width of 2x8s, 2x10s, and 2x12s reduces by 3/4", not 1/2". The difference between what we call these materials and their actual measurements can be perplexing, to say the least.

Diving into the history of these terms and common idioms often reveals fascinating stories. Take, for instance, phrases like "don’t look a gift horse in the mouth" or "don’t let the cat out of the bag." Each has a unique origin that gives depth to these seemingly casual expressions. Exploring the etymology behind these idioms sheds light on their original meanings, sometimes vastly different from how we use them today. In a way, they undergo a transformation akin to the evolution of a humble 2x4.

Historically, lumber mills initially cut materials precisely according to their dimensional names. A 2x4 was indeed a 2-inch by 4-inch cut. However, challenges arose due to the merging of various wood species and the absence of consistent kiln drying processes. As a result, different types of lumber began to shrink at different rates. There might have been variations in sizes that were originally cut to 2”x 4”, leading to inconsistencies in the market.

To address this, standardization emerged in the 1920s. Engineers likely scrutinized the smallest stable size that met structural standards. Meanwhile, sellers discovered that even a quarter-inch reduction in dimensions meant significant savings in transportation and storage costs. Consequently, the lumber sold under dimensional terms became known as "nominal sizes," a convention that has persisted through the years and is now a norm in the industry.

The journey of these lumber sizes and the nomenclature shift from actual measurements to nominal sizes presents an intriguing narrative—one that mirrors the evolution of language and common sayings. Exploring these historical nuances often reminds me of the saying, “I can’t see the wood for the trees,” suggesting that sometimes, the small details obscure the bigger picture. Although this is definitely not the case for me.

Stay tuned for more insights from me, Bob Johnson, A.K.A. Bob the builder.