Low permeability facade coatings reduce moisture in concrete

Abstract

Most of the exterior walls of houses in Iceland are of concrete. The climate is relatively wet, particularly in the south and freeze-thow cycles are quite frequent. High moisture content in the concrete of the walls is a prime cause of the serious damages that occur widely. The effect of coatings on the moisture content has been investigated for typical exterior walls. The experimental results presented indicate strongly that the moisture can best be reduced by using highly impermeable coatings on the exterior surfaces, that allow the concrete to lower its moisture content somewhat by shedding moisture into the houses. This is very much contrary to the generally accepted idea of using highly permeable coatings to allow the egress of water vapour from the interior of the structure. A resultant possibility is the use of very durable, high-build, crack-bridging elastomeric coatings that promise great benefits for house owners.