Section R601 of the IRC prescribes wood framing requirements for residential buildings. Floor systems are typically 2x6 or 2x8 joists spaced 16 inches on center. Wall framing uses 2x4 or 2x6 studs at 16-inch or 24-inch spacing depending on load. Headers above windows and doors must be sized to carry floor loads above. Roof framing uses rafters or trusses to support loads. Wall bracing resists lateral loads from wind and earthquakes. Bracing methods include let-in diagonal bracing, shear walls, and modern portal frame bracing. Connections between members use nails, bolts, or metal fasteners. Wall top plates are doubled at most locations to support joists above. Band boards or rim joists close off open joist ends.