The stiffness properties of timber depend on the timber type (solid, glued, …) and the climatic conditions (temperature, moisture variations). The effect is taken into account by the factor kdef.
According to Eurocode
- Values for kdef are given in EN 1995-1-1 Table 3.2.
- kdef is used to calculate the final mean values of the stiffness properties according to EN 1995-1-1 §2.4.1.
| Design values | Mean values | Final mean values |
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![\[ E_d=\frac{E_m_e_a_n}{\gamma_m} \]](https://support.buildsoft.eu/wp-content/ql-cache/quicklatex.com-7e5b29ebc6e0ec75595822cc511baed8_l3.png "Rendered by QuickLaTeX.com")
![\[ E_m_e_a_n \]](https://support.buildsoft.eu/wp-content/ql-cache/quicklatex.com-82e289b8968154f45ad5ec1be39b0457_l3.png "Rendered by QuickLaTeX.com")
![\[ E_m_e_a_n_._f_i_n=\frac{E_m_e_a_n}{1+\Psi_2 k_d_e_f} \]](https://support.buildsoft.eu/wp-content/ql-cache/quicklatex.com-51367449cf9dab997e3510c6680bb074_l3.png "Rendered by QuickLaTeX.com")
![\[ G_d=\frac{G_m_e_a_n}{\gamma_m} \]](https://support.buildsoft.eu/wp-content/ql-cache/quicklatex.com-89a4c1912d2d69bfdfbfb9716c4371b6_l3.png "Rendered by QuickLaTeX.com")
![\[ G_m_e_a_n \]](https://support.buildsoft.eu/wp-content/ql-cache/quicklatex.com-7170a36c93c913222a250588ad821b62_l3.png "Rendered by QuickLaTeX.com")
![\[ G_m_e_a_n_._f_i_n=\frac{G_m_e_a_n}{1+\Psi_2 k_d_e_f} \]](https://support.buildsoft.eu/wp-content/ql-cache/quicklatex.com-9742465f43306a1f8a6814a409ac9f82_l3.png "Rendered by QuickLaTeX.com")
In Diamonds
- The values for kdef are implemented in the material library of Diamonds.
- When you check the option ‘Take creep into account’ after clicking
, the final mean value for Young’s modulus 
will be used. 
is set equal to 1.
Note: PowerFrame cannot take kdef into account. Only Diamonds can.
