Timber Deflection

Background information on deflection calculations for timber structures.

Calculation Method

Timber deflection is calculated according to Eurocode 5: EN 1995-1-1.

Deflection Components

• Instantaneous deflection - Immediate deformation under load
• Creep deflection - Long-term deformation due to sustained load
• Final deflection - Total deflection including creep effects

Creep Factor (kdef)

The creep factor depends on:

• Service class (moisture conditions)
• Load duration class

Deflection Limits

Standard deflection limits according to Eurocode 5:

• Instantaneous: L/300 to L/500
• Final: L/150 to L/300

Where L is the span length.