On-site assessment method of air cavities attached to the foundations of historic buildings

Abstract

Air cavities have quite often been used to reduce underground capillary humidity in buildings of heritagevalue. The design of these cavities is not supported by objective criteria which ensure they work properly.This study aims to present a method for on-site evaluation so as to understand the workings and evaluatethe efficiency of the different kinds of cavities found in the Iberian Peninsula. It is a qualitative andsemi-quantitative method, which has been specifically designed, based on the formal, construction andperformance aspects of such systems. This process is supported by basic instrumentation and a highlyaccessible tool for calculation, and has been used on-site in more than eight cavities with satisfactoryresults. Analysis of the data collected has enabled an approach to the air dynamic in the cavities and theevaporation capacity. On the basis of a classification of types (which did not exist before), the simplemethod for research proposed here allows the evaluation of the functioning of air cavities on-site. A newand basic instrumentation is used which includes evaporimeters to calculate the cavities’ capacity of evaporation.