40×90

40x90 is a common designation for a specific size of lumber, particularly in the United States and Canada. It refers to the nominal dimensions of a piece of lumber before it has been dried and planed. In this case, the nominal thickness is 40 millimeters and the nominal width is 90 millimeters. However, lumber is typically sold and measured in inches, and these metric dimensions are often approximated or converted for ease of use in North American markets.

The actual finished dimensions of a piece of lumber designated as 40x90 will be smaller than its nominal size due to the milling process. For instance, a standard 2x4 in the US is nominally 2 inches by 4 inches, but its actual dimensions are closer to 1.5 inches by 3.5 inches. While 40x90 is less common than imperial measurements like 2x4 or 2x6, it represents a specific cross-section that may be encountered in certain construction or woodworking applications, especially where metric building standards are referenced or integrated.

The use of 40x90 lumber would depend on the specific structural requirements and design specifications of a project. Its dimensions suggest a moderate thickness and width, suitable for various framing, sheathing, or finishing tasks. The precise actual dimensions would need to be confirmed with the supplier or manufacturer, as drying and planing processes can lead to slight variations.