Floor joists are solid-sawn wood structural members. They typically are supported at each end by a foundation or girder. Floor joists are placed 12-in., 16-in., 19.2-in., or 24-in. on center.

A grademark identifies the species, grade, grading agency, and mill number. This information allows the product to be traced to the mill of origin, as well as establishing the structural properties of the piece of lumber
Most 2x4 dimension lumber is visually graded and marked with an ink stamp at the mill. The markings on this bunk of lumber provide information to ensure the product has the strength for the application.
Oriented Strand Board (OSB) is used to sheath lumber joists. The joists are supported by lumber headers. Builders may use bridging to maintain floor joist spacing.
Lumber joists are supported in metal joists hangers that are nailed to the face of a large LVL header.
Joist hangers are manufactured specifically for lumber and engineered wood products. These joist hangers have nail holes for connecting it to the lumber joist and the LVL girder.
Lumber floor joists are supported by joist hangers attached to an LVL girder. The LVL girder is supported in a heavy metal hanger that attaches to another LVL girder, which bears on a wall.
Lumber is commonly available in nominal 2" thickness and widths of 4" to 12".
OSB floor and wall sheathing is combined with lumber floor joists, wall studs, and headers in this traditional whole-house framing package.
Elements of a floor framing system.
IBS bridging is a manufactured wood bridging product that can be used with solid sawn joists to increase stiffness and reduce bounce and vibration.