Stone

Another classic that cannot be missed. Unquestionably impeccable. Let us simply highlight the potential that you can get resorting to a simple curtain wall but with few decisive variations: the exceptional glass -curvature, texture, roughness-; its format and size; and the lack of collinearity between mullions and transoms, enhancing horizontality. All of them contribute to accompany the gesture of both volumes towards the sea. The position of the two blocks, the volumetry and the facade definition, they all talk about the same.

It is not easy solving the entire envelope of the building, facade and roof, with a continuous mantle of variable slopes from 0% to 100%. If the tightness in the facade plane has been entrusted to geometry and drainage, where gravity acts in our favour; in the roof that solution will not be possible. The changes of slope in a topography of rounded ridges, generates practically zero slope planes, which can only be resolved with absolutely waterproof materials.

It is not watertight, it is not airtight. Depending on the density and sizes of the stones, it protects against direct sun radiation but without allowing the management of the visual relationship with the exterior. It considerably blocks the entry of light, gives privacy and protects from intrusion. If it is true that, together with a drained camera, it would then constitute a correct watertight envelope, but it seems that this is not the case here.

It is not possible to talk about facades without mentioning a very unique façade for the moment when it was built, and that even today continues being a reference.

The first point that draws our attention is the constructive system of own design, lightweight, based on a system of mullions (similar to a curtain wall). Despite the verticality imposed by the system, clearly visible from the outside elevation, the interior gives a fairly conventional image of blind parapet and horizontal windows. 

An excellent proposal for solving a façade composition with a rectangular format checkerboard pattern (the different areas, blind and hollowed, are only touched at the apex) avoiding the presence of the slab.

Whoever has faced this situation will know how difficult it is to unite at a vertex two openings placed in different floors, and therefore separated by a slab, without showing the thickness of this structural element.

The new building for the Dexeus Institute in Barcelona is one of the cases in which the openings completely divide the façade into horizontal strips. The façade is thus not mechanically interrupted by the main structure but by the openings. On each floor, the parapet made of reinforced brickwork is supported on the slab and stabilized against horizontal loads fixed to the pillars, while the wall above the window hangs inserted in a steel structure from its upper slab. The horizontal strip of openings needs to allow for differential movements of each part of the façade.

The Hotel Omm facade seems to us an interesting case study in many regards. It was a wise strategy to orient the openings towards the main avenue, Passeig de Gràcia, thus avoiding prying eyes from the building on the opposite side of the street as well as direct solar gain. Also, the bold materialization of this strategy involved transforming the outer layer of a rain screen façade into a series of lightweight walls that emerge from the façade as fish scales.

Years after the construction of the AC hotel in the Forum area, the one in Sants was built. The constructive solution adopted for the rain screen facade is practically the same in both cases. Again a lightweight enclosure when the use demands low thermal mass solutions.Again a reinforced frame supporting the window as the necessary structure to release an opening in this unidirectional facade structures. This frame, originally conceived to assume tolerances between the brick wall and the window, far from losing its sense gains new functions in that sort of facades.

If the inner layer of the rain-screen façade at the Hotel AC was innovative, it was still more innovative the proposal for the neighboring office tower for the Zona Franca Consortium. Again the exterior image is a sober stone skin anchored over aluminum profiles; but on this occasion the inner layer made of boards over a steel framing was prefabricated, arriving to the site as panels.