A transient, one-dimensional,jinite-difference model is presented that predicts the coupled transfer of heat and moisture in a multilayer wall under nonisothermal conditions. The model can predict moisture transfer in the diffusion through the capillary flow regimes. It has a provision to account for convective moisture transfer by including embedded cavities that may be coupled to indoor and outdoor air. The model is subsequently used to predict the timevarying average moisture content in• the sheathing and siding of a wood-frame wall as a junction of time of year. Results are shownfor a mild winter climate (Atlanta, Ga.), an intermediate winter climate (Boston, Mass.), and a cold winter climate (Madison, WIS.). The indoor temperature is maintained at 21°C, and separate computer runs are carried out for indoor relative humidities of 35% and 50%. The effect of several construction parameters on the winter moisture accumulation is investigated. The parameters include the interior vapor retarder permeance, sheathing penneance, exterior paint permeance, indqor air leaknge, and the amount of insulation.

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