Our first work of concrete in Mar Azul was well received and after many houses built with the same material placed, and always in the forest, we were commissioned to make a house using concrete near to the beach. We hesitate at the beginning of using the same aesthetic and constructive system as it has born in relationship with the original environment, but finally we agree thinking we can make the necessary arrangements to use this system in such a different environment: the dune where the beach ends. It was fundamental to optimize the thermal insulation in a place subjected to sunlight in summer and winter and to a wet, cold and strong gusts of wind and rain.The resource to make it possible was: propose a house where the roof can be expansions of different locals, putting decks of wood over the slab, allowing different outdoors activities and operating as an “Umbrella” that prevents from sunbeams (as would be done by the forest in the other houses). We also have to control the effect of glare which produce the sunbeams when they reflect in the sand. We decided it was not convenient to make openings from floor to roof and that they must be protected with eaves apart from have control of their shape and position in relation with the path of the sun and the dominant winds. With these fundamental premises, we start the project of “House in the Beach”.