What type of nail is typically used in floor installation?

In floor installation, 7d or 8d threaded/cut steel nails are commonly used due to their strength and durability, which are essential for securely attaching the flooring material to the subfloor. These nails provide the necessary holding power to withstand the weight and movement that floors endure over time. The diameter and length of these nails are ideal for penetrating through the flooring material into the subfloor without splitting the wood, thereby ensuring a solid installation.

The other options, while useful in different applications, do not provide the appropriate strength for flooring. Finishing nails are typically used for trim work and do not offer sufficient holding power for flooring. Brad nails are meant for lightweight applications and are not sturdy enough for heavy floor loads. Staples can be used for some flooring types, particularly carpet padding, but they are not the standard fastener for solid or engineered wood flooring installations where threaded/cut nails are preferred for their resilience and stability.