Simulation of drying of wood-frame walls submitted to water infiltration

This paper presents hygrothermal modeling results simulating the drying performance of different wood frame wall configurations submitted to water infiltration in the stud cavity. As rain can be the most important potential source of moisture in wall assemblies, an experimental investigation was previously undertaken at Concordia University to compare the wetting and drying potential of 15 walls subjected to water insertion in the stud cavity within a large Environmental Chamber. The experiment considered three different types of sheathing – oriented strand board (OSB), plywood and fiberboard, two exterior claddings – wood cladding on furring and cement stucco on metallic lath (no air space), and two different interior finish permeances – paint with/without polyethylene sheet. The moisture distribution in each wall was monitored using moisture content probes and gravimetric measurement and the conditions (exterior and interior) were controlled to reproduce August through November weather conditions for Montreal. The moisture load consisted in a wetted sill plate inserted into the wall assembly. The initial conditions for the simulation include the measured moisture distribution in the wood sill. The changes in moisture distribution in the wood sill and in the rest of the wall assembly are simulated taking into account proper boundary conditions. The simulation results are compared with the measured results. It was found that the type of cladding has the most impact on the drying performance. The role of the type of sheathing and of the level of interior finish permeance are also demonstrated and explained.