This calculator allows the user to assess the structural integrity of timber beams to ensure compliance with the Australian Standard AS 1720.1:2010. The calculation will identify the design capacities of timber beams to meet flexural, shear and deflection design requirements to Ultimate Limit State (ULS) and Serviceability Limit State (SLS) methods.
❗This calculation has been written in accordance with AS1720.
Australian Standards set out guidelines and minimum requirements for material properties, design parameters, design procedures and calculation methods. Here, we explain some pertinent timber properties that should be understood and carefully considered when undertaking timber design calculations.
Design Properties of Structural Timber Elements
Design capacities for all structural timbers are obtained by modifying characteristic capacities with factors appropriate to service conditions and material property type. This process applies to all types of timber.
Member Design Capacity (Rd)
Characteristic values (f'o)
Capacity Factor (ϕ)
Geometric Properties (X)
Modification Factors (Kmod)
Checking Limit States
AS1720.1 provides detailed guidelines for Ultimate Limit State (ULS) design. The calculation methods for design bending moment, shear and bearing capacities of structural timber members, joints and fasteners are robust enough to account for different scenarios and environmental factors. Permissible allowable stress limits or design limit capacities of timber beams are then calculated for each check by multiplying the relevant characteristic properties, modification factors and geometric properties together: