What does L/480 deflection equate to?
L/ is a ratio of deflection versus the length of the member in inches. For example: a 10′-0, or 120″, structural member that is L/480 can deflect a maximum of 1/4″. The length in inches is simply divided by the deflection factor, 120″/480 = .25″. Deflection factors are typically referred to in terms of live load deflection. Code requires a minimum of L/360 live load deflection for floor systems. However, Lumber Specialties typically designs floor systems at L/480 to improve floor performance. Remember, the higher the L/ factor, the lower the deflection.
