Moisture transport in wood - model to create input data to estimate the risk of mould growth and rot

To predict the risk if mould growth, rot, deformations and cracks in wood, it is necessary to know the moisture levels in constructions and building components. This paper presents a theory and a two-dimensional PC-model based on the use of Kirchhoff potentials to calculate moisture flow in wood. Anisotropy is allowed for using different flow coefficients in the different directions, in both sapwood and heartwood. The theory also deals with the internal boundary between sapwood and heartwood, and the external boundary to the outer air. The discrete form of the partial differential equation and the numerical technique to solve the problem are presented. The values of the flow coefficients used in the model are based on direct laboratory measurements. Calculation results from the model are compared with independently measured two-dimensional moisture distributions. The agreement is good. The output data from this model should be used as input data in risk models for mould growth and rot.