Section R505 specifies wall framing requirements using prescriptive stud sizes and spacing. Studs are typically 2x4 or 2x6 spaced 16 inches or 24 inches on center. Spacing depends on stud size, lumber grade, and story height. Two-story buildings typically use 2x6 studs or 2x4 studs with limited spans. Top plates are doubled to distribute loads. Bottom plates are single 2x4 lumber. Corner studs are tripled or use backing blocks for drywall attachment. Full-height studs are required (studs cannot be spliced mid-height except under specific conditions). Headers above windows and doors must be sized for load, with size increasing with header span. Cripple studs above and below windows support the header and sill.