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The 2 by 4 is the most common piece of wood in the world, but its dimensions are actually 1.5 by 3.5 inches, which can be misleading to many people, especially those outside of North America. The reason for this goes back more than a century ago when most dimensional lumber in the United States was produced by local manufacturers and only sold to customers in the vicinity of the mill. The mills produced rough lumber which was not uniform in width nor had standard dimensions. Builders were accustomed to manually planing the boards on site and making them fit the project.
As the forests near the larger cities were depleted by the late 1800s, lumber was no longer a locally made commodity and had to be shipped greater distances. At this point in time, railroad shipping was still extremely expensive, often double as expensive as the lumber itself, so the manufacturers had to get creative. They figured out that instead of shipping rough lumber which is then planed at the construction site resulting in tons of wasted material, they could instead provide the surfacing at the mill before shipping and in that way reduce the weight of the shipment. The opening of the Panama Canal in 1914 further complicated things. This new and considerably shorter shipping route made it possible for mills on the west coast to compete for the east coast markets.
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Misleading Dimensions of the 2 by 4
The 2 by 4, the most common piece of wood in the world, is actually not what the name suggests. Its dimensions are 1.5 by 3.5 inches. This can be misleading, especially to people outside of North America. The actual reason for this goes back more than a century ago when most dimensional lumber in the United States was produced by local manufacturers and only sold to customers in the vicinity of the mill.
The mills produced rough lumber which was not uniform in width nor had standard dimensions. The builders were accustomed to manually plane the boards on site and make them fit the project. By the late 1800s, the forests near the larger cities were depleted, so lumber was not a locally made commodity anymore and had to be shipped greater distances.
At this point in time, railroad shipping was still extremely expensive, often double as expensive as the lumber itself, so the manufacturers had to get creative. They figured out that instead of shipping rough lumber, which is then planed at the construction site resulting in tons of wasted material, they could instead provide the surfacing at the mill before shipping and in that way reduce the weight of the shipment.
The opening of the Panama Canal in 1914 further complicated things. This new and considerably shorter shipping route made it possible for mills on the west coast to compete for the east coast markets. Since ocean rates are based on volume, the wood manufacturers had an even greater incentive to start shaving off any volume they could. As a result, the manufacturer with the long haul tried to meet the competitor’s price by putting on the market thinner lumber, thereby equalizing the difference in the freight rates. They still called the product a 2 by 4 even though it was a smaller dimension. The justification was that the original rough lumber before surfacing was a 2 by 4 and therefore the final product could also be called a 2 by 4.
The continuous price wars caused the mills to push the thickness of the 2 by 4 down as much as the market would allow. The name 2 by 4 had a different meaning for every region in the US. The tables in the book “Lumber and Its Uses” from 1914 illustrate the dimensional mess perfectly. The dimensions varied based on the number of sides surfaced, intended use, wood species, location, and so on.
Filling up their stockpiles with different versions of 2 by 4s impeded their business, so naturally, they were the ones that pushed hardest for a nationwide standard. As a consequence, the Department of Agriculture in 1919 set out the Forest Products Laboratory to investigate which dimensions would be most suitable to be adopted as a standard.
They found out that more than 60% of the producers were surfacing the 2-inch side of their boards down to 1-5/8, so it was natural to make this dimension a National Standard. Furthermore, they concluded that 1-5/8 is the optimal size for joists and studs and that anything above this dimension would add to the cost but not increase its usefulness. The claim that 1-5/8 by 3-5/8 was the optimal size is debatable at best. Any size can be made optimal by adjusting the spacing of the joists or studs. Though that would likely result in very awkward spacing dimensions.
Today, a 2 by 4 does start off as a rough cut 2 by 4, but after drying and surfacing, the final 1-1/2 by 3-1/2 dimension is achieved, which is the one available for purchase in a retail store. In conclusion, the current sizes are well-suited for light-frame construction, roofing joists, and other smaller projects. This history is applicable to all dimensional lumber sizes, but the 2 by 4 was singled out as the most common.
Historical Context of Lumber Production
The dimensions of a 2 by 4 board are actually 1.5 by 3.5 inches. This misleading name dates back to the late 1800s when most lumber in the United States was produced by local manufacturers and only sold to customers in the vicinity of the mill. The builders were accustomed to manually planing the boards on site to fit the project, as the rough lumber was not uniform in width nor had standard dimensions. However, as the forests near the larger cities were depleted, lumber had to be shipped greater distances, which was extremely expensive at the time.
To reduce the weight of the shipment and shipping costs, manufacturers started to provide surfacing at the mill before shipping. This meant that the lumber was thinner than the rough lumber, resulting in the name 2 by 4 being used even though it was a smaller dimension. The name 2 by 4 had a different meaning for every region in the US, and the dimensions varied based on the number of sides surfaced, intended use, wood species, location, and more.
The retail dealers were not happy with the situation, as it impeded their business, so they pushed for a nationwide standard. As a consequence, the Department of Agriculture in 1919 set out the Forest Products Laboratory to investigate which dimensions would be most suitable to be adopted as a standard. They found that 1-5/8 by 3-5/8 inches was the optimal size for joists and studs and that anything above this dimension would add to the cost but not increase its usefulness.
The standard had a bigger problem to deal with, and that was the moisture content specification, which was very hard to enforce at this point in history since it was difficult to measure the moisture content of the lumber. As a result, mills started to surface the lumber green, meaning while it’s still wet and bulky, and ship it off as such. When the boards would dry up, its size would shrink down to below the standard dimension.
During World War II, lumber was in short supply, and manufacturers tried to produce lumber as cheaply as possible, in many cases, deviating from the standard. The trend of ever-thinner lumber continued after the war, and in the late 50s and early 60s, a standard was once again open for discussion. In 1963, the American Lumber Standards Committee approved the new standard of the 2 by 4, which was 1-1/2 by 3-5/8 inches. This dimension was later amended once more to the final size used today.
Today, a 2 by 4 starts off as a rough cut 2 by 4, but after drying and surfacing, the final 1-1/2 by 3-1/2 dimension is achieved, which is the one available for purchase in a retail store. The current sizes are well-suited for light-frame construction, roofing joists, and other smaller projects. This history is applicable to all dimensional lumber sizes, but the 2 by 4 was singled out as the most common.
Impact of Transportation Costs on Lumber Sizing
The history of lumber sizing in the United States is closely tied to transportation costs. In the late 1800s, as forests near larger cities were depleted, lumber had to be shipped greater distances. However, railroad shipping was extremely expensive, often double the cost of the lumber itself. To reduce shipping costs, manufacturers began providing surfacing at the mill before shipping, reducing the weight of the shipment. This led to thinner lumber being produced, even though it was still called a 2 by 4.
The opening of the Panama Canal in 1914 made it possible for mills on the west coast to compete for east coast markets. Since ocean rates are based on volume, manufacturers had an even greater incentive to reduce the volume of their shipments. As a result, the thickness of the 2 by 4 continued to be pushed down as much as the market would allow.
During World War II, lumber was in short supply and manufacturers tried to produce it as cheaply as possible, often deviating from the standard. The trend of ever-thinner lumber continued after the war, with a new standard of 1-1/2 by 3-5/8 inches being approved in 1963. Today, a 2 by 4 starts off as a rough cut 2 by 4, but after drying and surfacing, the final dimension is 1-1/2 by 3-1/2 inches.
The decision to produce thinner lumber was driven by the need to reduce shipping costs, which were astronomical at the time. While some have questioned why mills don’t start with a slightly larger dimension and surface it down to an exact 2 by 4, the current sizes are well-suited for light-frame construction, roofing joists, and other smaller projects.
Standardization Efforts by Retail Dealers
Retail dealers were greatly affected by the lack of standardization in the lumber industry, particularly with the 2 by 4. The varying dimensions of the board made it difficult for them to stockpile and sell to customers. As a result, they pushed for a nationwide standard that would make it easier for them to conduct business.
In 1919, the Department of Agriculture established the Forest Products Laboratory to investigate which dimensions would be most suitable to be adopted as a standard. The investigation included 75 mills and extended consideration for the most economical thickness of lumber for both manufacturers and customers. The study found that more than 60% of the producers were surfacing the 2-inch side of their boards down to 1-5/8, making it natural to make this dimension a National Standard. Furthermore, it was concluded that 1-5/8 is the optimal size for joists and studs and that anything above this dimension would add to the cost but not increase its usefulness.
However, the standard had a bigger problem to deal with, and that was the moisture content specification, which was very hard to enforce at this point in history since it was difficult to measure the moisture content of the lumber. As a result, mills started to surface the lumber green, meaning while it’s still wet and bulky, and ship it off as such. When the boards would dry up, its size would shrink down to below the standard dimension.
Despite the challenges, retail dealers were successful in their efforts, and a new standard was established in 1963, which set the dimensions of a 2 by 4 to 1-1/2 by 3-5/8 inches. This dimension was later amended once more to the final size used today, which starts off as a rough cut 2 by 4 but after drying and surfacing achieves the final 1-1/2 by 3-1/2 dimension available for purchase in a retail store.
In conclusion, the standardization efforts by retail dealers played a crucial role in establishing a nationwide standard for the 2 by 4 and other dimensional lumber sizes. This standardization made it easier for retail dealers to conduct business and for customers to purchase lumber with consistent dimensions.
National Standard Adoption by the Department of Agriculture
In 1919, the Department of Agriculture established the Forest Products Laboratory to investigate the most suitable dimensions for lumber to be adopted as a national standard. The investigation included 75 mills and considered the most economical thickness of lumber for both manufacturers and customers. The laboratory found that more than 60% of the producers were surfacing the 2-inch side of their boards down to 1-5/8 inches, so it was natural to make this dimension a national standard. The laboratory also concluded that 1-5/8 inches is the optimal size for joists and studs, and anything above this dimension would add to the cost but not increase its usefulness.
However, the claim that 1-5/8 by 3-5/8 inches was the optimal size is debatable. Any size can be made optimal by adjusting the spacing of the joists or studs, but that would likely result in very awkward spacing dimensions. Furthermore, loading conditions across the US are so vastly different that what is optimal for one region may not be optimal for another.
Despite these issues, the national standard was established, and in 1963, the American Lumber Standards Committee approved the new standard of the 2 by 4, which was 1-1/2 by 3-5/8 inches. This dimension was later amended once more to the final size used today.
Today, a 2 by 4 starts off as a rough cut 2 by 4, but after drying and surfacing, the final 1-1/2 by 3-1/2 dimension is achieved, which is the one available for purchase in a retail store. The current sizes are well-suited for light-frame construction, roofing joists, and other smaller projects.
Optimality Debate and Moisture Content Challenges
The optimal size for joists and studs has been a topic of debate in the lumber industry for many years. The Department of Agriculture investigated 75 mills and found that more than 60% of producers were surfacing the 2-inch side of their boards down to 1-5/8, which they concluded was the most economical thickness for both manufacturers and customers. However, the claim that this size is the optimal size is debatable, as any size can be made optimal by adjusting the spacing of the joists or studs. Additionally, loading conditions vary across the United States, making it difficult to determine a one-size-fits-all optimal size.
Furthermore, the moisture content specification posed a challenge for the lumber industry, as it was difficult to enforce at the time. Mills began to surface lumber while still wet and bulky, which would shrink down to below the standard dimension as it dried. This downward pressure on the dimension of the 2 by 4 was further supported by the fact that ocean fares did not charge by weight but by volume.
Despite these challenges, the American Lumber Standards Committee approved a new standard for the 2 by 4 in 1963, with a dimension of 1-1/2 by 3-5/8 inches. This dimension was later amended to the current size of 1-1/2 by 3-1/2 inches. Today, the 2 by 4 starts off as a rough cut 2 by 4 but after drying and surfacing, the final 1-1/2 by 3-1/2 dimension is achieved, which is the one available for purchase in retail stores.
In conclusion, the optimal size for joists and studs remains a topic of debate in the lumber industry, and the moisture content specification posed a challenge for enforcing standard dimensions. Despite these challenges, the 2 by 4 has undergone several changes in size over the years and remains a commonly used piece of lumber in light-frame construction, roofing joists, and other smaller projects.
Dimensional Changes During the Great Depression and WWII
During the Great Depression in 1929, the demand for lumber significantly decreased, resulting in no major changes or push for a new standard for about 10 years. However, during World War II, lumber was in short supply, and manufacturers tried to produce lumber as cheaply as possible, often deviating from the standard dimensions. There was also a widespread belief that wood had ample reserve strength capacity, and further reducing the dimensions would not cause any significant problems.
The trend of thinner lumber continued after the war, and in the late 1950s and early 1960s, the standard for the 2 by 4 was once again open for discussion. Western manufacturers proposed a reduction in the 2-inch side down to 1-1/2 inches, while the 4-inch side would remain 3-5/8 inches, arguing that the thickness of the board did not affect the bending capacity of the joists much. Whether this was the decisive argument or the general will of the industry to go thinner is hard to tell.
In 1963, the American Lumber Standards Committee approved the new standard for the 2 by 4, which was 1-1/2 by 3-5/8 inches. This dimension was later amended to the final size used today. Today, a 2 by 4 starts off as a rough cut 2 by 4, but after drying and surfacing, the final dimension is achieved, which is 1-1/2 by 3-1/2 inches, available for purchase in a retail store.
It is reasonable to ask why the mills do not start with a slightly larger dimension and surface it down to an exact 2 by 4. However, the problem was never getting the correct dimension, but rather saving on material and mostly on shipping costs, which were astronomical back then. The current sizes are well-suited for light-frame construction, roofing joists, and other smaller projects. This history of dimensional changes is applicable to all dimensional lumber sizes, although the 2 by 4 was singled out as the most common.
Post-War Industry Trends and Standard Discussions
After World War II, the demand for lumber decreased significantly, causing manufacturers to produce lumber as cheaply as possible. In many cases, they deviated from the standard. However, there was a widespread belief that wood had ample reserve strength capacity, and reducing the dimensions would not cause any major problems. This trend of ever-thinner lumber continued after the war.
In the late 1950s and early 1960s, the standard was once again open for discussion. Western manufacturers proposed reducing the 2-inch side down to 1-1/2 inches while keeping the 4-inch side at 3-5/8 inches. Their argument was that the thickness of the board did not affect the bending capacity of the joists much anyway. The bending capacity is more influenced by the width since it is the cubed dimension in the moment of inertia formula. Whether this was the decisive argument or it was the general will of the industry to go thinner is hard to tell.
In 1963, the American Lumber Standards Committee approved the new standard for the 2 by 4, which was 1-1/2 by 3-5/8 inches. This dimension was later amended once more to the final size used today.
Today, a 2 by 4 does start off as a rough cut 2 by 4, but after drying and surfacing, the final 1-1/2 by 3-1/2 dimension is achieved, which is the one available for purchase in a retail store. The current sizes are well-suited for light-frame construction, roofing joists, and other smaller projects.
It is often asked why mills don’t start with a slightly larger dimension and surface it down to an exact 2 by 4. However, the problem was never getting the correct dimension but rather saving on material and mostly on shipping costs, which were astronomical back then. This history is applicable to all dimensional lumber sizes, but the 2 by 4 was singled out as the most common.
Final Standardization and Modern Dimensions
After decades of confusion and inconsistency surrounding the dimensions of the 2 by 4, the American Lumber Standards Committee finally approved a national standard in 1963. The new standard reduced the 2-inch side down to 1-1/2 inches while keeping the 4-inch side at 3-5/8 inches. This dimension was later amended to the final size of 1-1/2 by 3-1/2 inches that is used today.
Today, the 2 by 4 starts off as a rough cut 2 by 4 but after drying and surfacing, the final 1-1/2 by 3-1/2 dimension is achieved. This size is well-suited for light-frame construction, roofing joists, and other smaller projects.
It is often asked why mills don’t start with a slightly larger dimension and surface it down to an exact 2 by 4. However, as mentioned in the background information, the main reason for the current dimensions is to save on material and shipping costs. The current size is optimal for its intended uses and any larger size would only add to the cost without increasing its usefulness.
It is important to note that the history behind the 2 by 4 is applicable to all dimensional lumber sizes. The 2 by 4 was simply singled out as the most common piece of wood in the world.
Reasons Behind Maintaining the 2 by 4 Name
The name of the most common piece of wood in the world, the 2 by 4, is misleading as it does not actually have dimensions of 2 inches by 4 inches. The name dates back more than a century ago when most dimensional lumber in the United States was produced by local manufacturers and only sold to customers in the vicinity of the mill. The mills produced rough lumber which was not uniform in width nor had standard dimensions. Builders were accustomed to manually plane the boards on site and make them fit the project.
By the late 1800s, the forests near larger cities were depleted, and lumber was no longer a locally made commodity. It had to be shipped greater distances, and at this point in time, railroad shipping was still extremely expensive, often double as expensive as the lumber itself. To reduce the weight of the shipment, manufacturers figured out that instead of shipping rough lumber which is then planed at the construction site resulting in tons of wasted material, they could instead provide the surfacing at the mill before shipping. This resulted in the manufacturer with the long haul trying to meet the competitor’s price by putting on the market thinner lumber, thereby equalizing the difference in the freight rates. They still called the product a 2 by 4 even though it was a smaller dimension.
The justification was that the original rough lumber before surfacing was a 2 by 4 and therefore the final product could also be called a 2 by 4. At this point in time, the name 2 by 4 was not reserved for a specific type of board, so there was no legal standard that forced the mills to have a specific dimension for their 2 by 4s. The continuous price wars caused the mills to push the thickness of the 2 by 4 down as much as the market would allow. The name 2 by 4 had a different meaning for every region in the US.
Filling up their stockpiles with different versions of 2 by 4s impeded the retail dealers’ business, so they pushed hardest for a nationwide standard. As a consequence, the Department of Agriculture in 1919 set out the Forest Products Laboratory to investigate which dimensions would be most suitable to be adopted as a standard. They found out that 1-5/8 is the optimal size for joists and studs and that anything above this dimension would add to the cost but not increase its usefulness. The bending capacity is more influenced by the width since it is the cubed dimension in the moment of inertia formula.
In 1963, the American Lumber Standards Committee approved the new standard of the 2 by 4, which was 1-1/2 by 3-5/8 inches. This dimension was later amended once more to the final size used today. Today, a 2 by 4 does start off as a rough cut 2 by 4 but after drying and surfacing, the final 1-1/2 by 3-1/2 dimension is achieved, which is the one available for purchase in a retail store.
In conclusion, the reason for maintaining the name 2 by 4 is due to the historical significance of the name and the fact that it has become a standard that is widely recognized. The current sizes are well-suited for light-frame construction, roofing joists, and other smaller projects.
Applicability to Other Dimensional Lumber Sizes
The history of the 2 by 4 is not unique to this specific size of lumber. The same factors that influenced the dimensions of the 2 by 4 also influenced the dimensions of other types of dimensional lumber. The need to reduce shipping costs and waste material led to the standardization of lumber sizes.
The Forest Products Laboratory investigated the most economical thickness of lumber for both manufacturers and customers. They found that 1-5/8 inches was the optimal size for joists and studs, and that anything larger would add to the cost but not increase its usefulness. This conclusion applied not only to the 2 by 4 but to other sizes of lumber as well.
While the optimal size of lumber may vary depending on the region and loading conditions, the standardization of lumber sizes has made it easier for builders to plan and construct their projects. The current sizes of dimensional lumber are well-suited for light-frame construction, roofing joists, and other smaller projects.
Overall, the history of the 2 by 4 is a reminder of the importance of standardization in the lumber industry. By establishing standard sizes, manufacturers and builders can reduce waste and costs, and ensure that their products are consistent and reliable.