Casa S is a minimalist residence located in Valparaiso, Chile, designed by RUIZSOLAR Arquitectos. Through a cross language in the use of the inner and outer spaces, all four core premises that give order to the house meet on the house’s design program. In this way protected outer spaces, framed within the house, together with communicated inner spaces which are naturally included, are contemplated. The duality suggested in the use of space is also taken into consideration in the use of materials. The main material used for the outer spaces facades which are under the house protection is the 2×1 lining. For the main facades a lining whose geometry, volume and material contribute to a marked contrast is suggested, being this another expression of the foundational four core principles.