Only a hall with the highest requirements could host the rehearsals in Madrid of a symphony orchestra such as the California Symphony Orchestra. The acoustic solutions in bamboo and its high guarantees are the ones that meet in the New Oratory and Assembly Hall of the Retamar School.
It is here that the musicians have played taking advantage of the benefits of bamboo, the sustainable and acoustic material par excellence with which Grupo GUBIA has completely covered the interior of both spaces. The project, led by Hermoso and Heimannsfeld Architects, has transformed these two halls into a sanctuary of sound of more than 2,000m2. The development of the project has required a deep study, work and strategic manipulation of the material, in which GUBIA’s architects and carpenters are experts. Actually, with bamboo -as well as with any other wood species- they design and build both public and private spaces.
In this case, for the Retamar School in Madrid, an interior finish material such as bamboo has been selected. In addition to its environmental and ecological advantages and its aesthetic beauty, bamboo was chosen for its mechanical properties and flexibility. This plant, which is considered to be the vegetable steel, and which hardly needs reforestation due to its rapid growth, is also hard, resistant and extremely stable. The Sevillian studio has been working with bamboo for more than a decade in different formats and modalities (flooring, ceilings, plywood and flexible slats, solid boards, etc.) and, in this case, to clad the ceiling of the oratory, they have used thin 2400x100mm slats composed of seven veneers of GUBIA Cv – 0.6 vertical carbonized bamboo. Acoustic solutions in bamboo are a spectrum that the applied carpentry team is constantly developing and perfecting.
Roof layout and properties
These elongated, highly flexible 6 mm thick pieces are screwed at five points to an auxiliary metal structure, spaced 50 mm apart. This space is covered on top with a sound-absorbing material finished in black to achieve 100% acoustic transparency. The result is a beautiful, warm, highly absorbent surface that is indispensable for the uses to which this salt is put. At the same time, it shows a rich color contrast between the black of the acoustic material and the natural tone of the bamboo slats themselves.
The manager of the College and telecommunications engineer, Miguel Ortuño, comments that “the acoustics achieved in the oratory are really good. The reverberation of this type of space is usually multiplied by up to seven and, in this case, it has remained at around two. All this thanks to the absorption capacity of the bamboo”. He also explains that the array system, a group of acoustic boxes that open 120º and 15º vertically, has been installed in a hidden way. In this way, the aesthetics and design of the oratory have not been affected.
Acoustic bamboo testing
Since the beginning of the project, tests and computer simulations have been carried out to find the best acoustic solution for the space. The results obtained revealed that a zenithal direction of the same was the most optimal option (the one that added less noise). This, always reinforced and cared for through the absorbent properties of the bamboo behind which it hides. In addition, Ortuño adds, “in the end it was not necessary to lower the ceiling, as the acoustic boxes could be hidden behind the GUBIA bamboo slats because of their size”.
The curvature of the oratory ceiling is translated vertically into split planes also clad in bamboo on the different fronts of the nave, where the slats described above are combined with fireproof fiberboards finished with GUBIA Ch o.6 horizontal carbonized bamboo sheeting, laid across. In addition, for the confessional area, the architects have designed another original acoustic ceiling. This one is made up of black perforated fireproof fiber panels to which 100x19mm slats of GUBIA BSP 19 C-h board are fixed on edge.
Acoustic solutions in bamboo for the Conference Hall ceiling
Bamboo is also used in the school’s conference hall, which is located under the oratory floor. A new perforated acoustic ceiling is the main protagonist and guarantees optimum and adequate acoustic
In its design, trapezoidal panels finished in this material, developed by GUBIA with 13 mm thick fireproof plywood boards, have been placed with different inclinations previously studied by a professor of acoustic physics. The objective, according to the manager, “was to avoid sound bounce, achieving zero reverberation in the room, turning it into an anechoic chamber”. All these pieces float over the seating area in an asymmetrical dance and have countersunk perforations of 6 mm in diameter, in addition to sound-absorbing material in the upper area.
In short, Ortuño concludes, “since its completion, everyone has been really surprised by the acoustics of the oratory and the conference hall. Our team has done a very professional job on them, in view of the results. Otherwise, the prestigious California Symphony Orchestra would not have been able to rehearse in our facilities before performing in the Auditorio de Madrid”. The acoustic solutions in bamboo and its added sustainability make this project a reference in this field.