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Loading Class Manual for intelliVIEW – Chapter 2 Duration of Load Factor (Duration Factor) This is an adjustment to the allowable stress in wood members based on the duration; total length of time, the load causing the stress is applied to the member. The shorter the duration of time that the load is applied, the higher the percentage increase in allowable stress. Because of wood's structural properties, it can support higher loads for shorter periods of time. The Duration Factor approximates the total length of time that the maximum load is applied to the structure during its life. Factor Duration Typical Loads 2.00 2-Seconds Impact Load. This duration factor is to be used only with the engineer of record's prior approval, and never with connectors. 1.6 10 Minutes Wind and Seismic Loads. Consult building codes as some areas require 1.33 duration factor for wind loads. 1.33 2-3 Days Wind Loads. Consult building codes to determine if this duration factor is applicable to your area. 1.25 7 Days Construction and Roof Live Loads. Short term live loads. Typically not applicable for loads resulting from Snow. 1.15 2 Months Snow Load. Typically, snow in a climate that would not allow melting for a period of time. 1.00 10 Years Floor Live Load. This is the standard Duration Factor used where floor live loading is applicable. 0.90 50 Years Dead Load. Applies to conditions where all or the majority of the applied load is dead load. A typical condition would be a member that carries brick. Consult with engineer of record before using this duration factor.