Changes in Subgrade Insulation Conductivity With Varying Moisture Content

The climate is rapidly changing, raising the groundwater level and causing more severe flooding. As flood waters rise, they saturate the soil and penetrate foundations. In Canada, there are two ways of insulating a foundation: externally against the soil or internally, like in a wall assembly. The saturation of external insulation by flood waters will change its thermal conductivity, but the effects of cyclic wetting and drying have not been well documented. There are two aspects to the study of this impact, WUFI simulation and lab testing. Three types of insulation were used in the lab testing, extruded polystyrene (XPS), closed-cell polyurethanesprayfoam,and rockwoolmineral wool,whichcanall be usedinground contact.Thepurpose is to determine if insulation can return to its pre-wetted thermal conductivity after several flooding events. The results are promising, but this topic will need to be studied over a longer period.