Building structures often contain cavities or strips of air. Because of this, it is difficult to describe the transfer phenomena that are in fact heat transfers (conductive, convective and radiative), as well as mass transfers through porous media. Numerous studies have dealt with each of these transfers separately but few have managed to describe the interrelation between them. This paper represents an initial approach to the problem, by attempting to describe the influence of the moisture level on heat transfers occurring through hollow vertical terra-cotta bricks. A theoretical modeling of exchanges has been carried out in order to determine radiative and convective exchanges coefficients. A mass exchange coefficient has then been deduced. The results obtained show a high sensitivity of the heat flux to the moisture level of the surroundings.