SPF lumber is a type of lumber that combines spruce, pine, and fir from North America, primarily Canada. The term SPF is an acronym for "Spruce-Pine-Fir," which refers to any of these types of coniferous trees grown and harvested in various regions of North America. The spruce, pine, and fir species comprising the SPF category all produce high-grade timber with relatively small, sound tight knots and a color that ranges from white to pale yellow. SPF lumber is used widely in North America for wood-frame construction, including single and multi-family home construction, commercial construction, crafting and packaging, and furniture framing. Its superior strength-to-weight ratio and competitive pricing make it a popular choice for wood framing in furniture, houses, apartments, trusses, and commercial buildings. SPF lumber is classified into two distinct species, namely Eastern and Western. The most common nominal sizes of SPF that can be found in most lumber yards include 2x3, 2x4, 2x6, 2x8, 2x10, and 2x12. SPF lumber is not typically used in finishing work, furniture, or cabinetry, but many woodworkers still choose to use it, and it can be used to make beautiful projects when handled properly.