Prediction of Density for Prevention of Settling of Hygroscopic and Nonhygroscopic Loose-fill Insulation in Walls

Abstract

This paper discusses the prediction of the density necessary for the prevention of the settling of hygroscopic and nonhygroscopic loose-fill insulation in walls, when the criteria for creep in granular materials are applied. The practical use of a theoretical framework presented earlier and the material characteristics used to develop an equation from which the necessary density can be predicted, are described. The empirical framework allows a quantitative approach to the problem of achieving nonsettling of a loose-fill insulation material in a given wall. The study involves the use of empirically derived equations to predict the density of a loose-fill insulation material required to ensure volume stability in a wall exposed to one type of cyclical humidity conditions. An empirical model for predicting the creep of materials has been developed in earlier papers. The creep was determined from the corresponding tests. The use of the method is demonstrated by showing the results from a full-scale wall test. The method is applied for different cavity sizes together with the associated characteristics of four hygroscopic and one nonhygroscopic loose-fill insulation materials exposed to the same climatic conditions. In addition, it is shown that for many repeated cyclical humidity conditions, the creep of the hygroscopic and nonhygroscopic loose-fill insulation materials asymptotically approached equilibrium.