2by4 nominal actual © Holzkurier.com
In North America, the dry volume unit board foot, which is one square foot (30.48 cm by 30.48 cm) by one inch (2.54 cm), is commonly used for lumber:
1 board foot = 1 ft × 1 ft × 1 in = 12 in × 12 in × 1 in = 30.48 cm x 30.48 cm x 2.54 cm
One thousand board feet should therefore be around 2.36 m³ of lumber, correct? Unfortunately, it isn’t in most cases.
In North America, most of the softwood lumber is sold to timber construction companies as so-called dimensional lumber, which used to be fresh, unplaned wood, usually with a cross-section of 2 x 4 inches. At some point, dry, planed wood became the new dimensional lumber. In practice, this meant subtracting a quarter inch of planing allowance on each side. Nominally, the product is still called 2-by-4 (nominal size) but in reality (i.e. actual size), it measures only 1.5 x 3.5 inches – that is 34% less than what its name suggests.
One thousand board feet of this dimensional lumber are only 1.55 m³. In other words, you have to increase by a factor of 1.52 (2-by-4 in relation to 1.5 x 3.5) to compare US with European softwood lumber prices. Similar conversion factors apply to other construction products, such as 2-by-6, for example.
Real-life calculation example
In mid-March 2022, 2-by-4 cost US-$1,400/1,000 bft – or €1,272/1,000 bft with the then currency rate of US-$1.1/€.
Nominally, 1,000 bft are 2.36 m³. So, the next calculation is: 1,272 divided by 2.36. Converted into nominal cubic meters, this is €539/m³.
On the US market, however, billing is done based on “actual size”. Therefore, you have to take the difference between actual size and nominal size into account. The conversion factor is 2 times 4 divided by 1.5 times 3.5 – i.e. 1.5238.
The last step involves multiplying €539/m³ times the factor 1.5238 which equals around €820/m³.
