ISO/TC 163/SC 1/WG 8 - Moisture content and moisture permeability

This document specifies two alternative methods for determining hygroscopic sorption properties of porous building materials and products: a) using desiccators and weighing cups (desiccator method); b) using a climatic chamber (climatic chamber method). The desiccator method is the reference method. This document does not specify the method for sampling. The methods specified in this document can be used to determine the moisture content of a sample in equilibrium with air at a specific temperature and humidity.

This document specifies the test method of moisture-adsorption/desorption efficiency (or capacity) of building materials, when there are changes in temperature in sealed boxes containing building materials.

ISO 12572:2016 specifies a method based on cup tests for determining the water vapour permeance of building products and the water vapour permeability of building materials under isothermal conditions. Different sets of test conditions are specified. The general principles are applicable to all hygroscopic and non-hygroscopic building materials and products, including insulation materials and including those with facings and integral skins. Annexes give details of test methods suitable for different material types. The results obtained by this method are suitable for design purposes, production control and for inclusion in product specifications.

ISO 16957:2016 describes a method of measuring the thermal conductivity (diffusivity) of a wet porous building material and a method of evaluating the measurement uncertainty. While ISO 10051 is the current International Standard, based on a steady-state method, ISO 16957:2016 proposes a method that makes use of a non-steady-state method which uses a small temperature change with a short period as an input. Along with the measurement, an evaluation of the measurement uncertainty is described, which makes possible a simple and practical measuring method. ISO 16957:2016 intends to measure the apparent (effective) thermal conductivity, including latent heat transfer caused by vapour movement. The situation in which moisture and/or air movement occur due to convection or gravity is excluded. The application of ISO 16957:2016 to high moisture content is excluded so that the gravity effect can be neglected. ISO 16957:2016 can be applied to a porous material heavier than about 100 kg/m3, in which radiative heat transfer can be neglected. It specifies the following: a) a non-steady-state method of measuring thermal conductivity; b) an approximation formula for the measurement uncertainty caused by moisture movement and nonuniform moisture distribution (and, thus, a determination of the measuring conditions that satisfy the upper limit of measurement uncertainty); c) an estimate of the heat transfer caused by moisture (vapour) movement.

ISO 12571:2013 specifies two alternative methods for determining hygroscopic sorption properties of porous building materials and products: a) using desiccators and weighing cups (desiccator method); b) using a climatic chamber (climatic chamber method). The desiccator method is the reference method. ISO 12571:2013 does not specify the method for sampling. The methods specified in ISO 12571:2013 can be used to determine the moisture content of a sample in equilibrium with air at a specific temperature and humidity.