Concrete proved a critical choice for the main structure of this performing arts academy, both containing noise and reducing vibration from the dance studios
‘Acoustics were a major consideration from day one,’ says Turner.Works’ Carl Turner of Mountview Academy, a £22.5 million new performing arts school in Peckham, south London. Shortlisted for an RIBA London 2020 Award, the Academy provides 10,365m2 of teaching, rehearsal and performance facilities adjacent next to Will Alsop’s 2000 Stirling Prize-winning Peckham Library.
Working with theatre consultants and acoustician Charcoalblue, Turner.Works certainly had an acoustic challenge on its hands. Site-wise, the team had to contend with street noise from its busy location in the centre of Peckham, but was also mindful of not irritating the Academy’s neighbouring residents.
In terms of programme, the building needed to accommodate a diverse mix of uses with all the acoustic complexities of adjacencies that these entailed – acoustic clash was a key concern as the configuration of accommodation was moved around during the design.
Arranged in two interlocking Studio and Theatre blocks, the Academy includes 21 studios for dance and drama, recording suites, offices, a café/restaurant, and a 200-seat main theatre and scenery workshop. Added to this mix is the noise and energy of some 400 performing arts students as they circulate and hang out in the main atrium. ‘It’s an incredible noisy showcase for the performing arts,’ says Turner.
And on top of all that, both budget and programme were exceedingly tight. At £2210/m², the budget was reckoned by Turner to be ‘about half’ what you’d expect for a typical performance building. In addition, the project took just three years from start to finish, including 18 months on site, despite several redesigns including one in response to safety concerns following the Grenfell fire.
‘One of the challenges we faced was finding a balance between the very tight budget, stringent acoustic requirements and a very fast build programme,’ says Turner.
The pragmatic solution was to provide a sensible base level of acoustic performance for each space, on the understanding that as the building was occupied, some ‘hot spots’ might emerge that would need remediating.
The choice of concrete over CLT for the main structure was fundamental to achieving the acoustic performance required for such a density of sound-sensitive spaces. Concrete provided not only sufficient thermal mass, but also the necessary stiffness to dampen movement – a particularly important consideration given the inclusion of the many dance studios at the Academy.
Another key design factor was that the building was naturally ventilated. In the Corten-clad studio block, air is drawn through the studio via external louvres in the walls, and out into the atrium. This operates as a stack effect, drawing air up and out through louvres located on the sides of the roof light lantern.
Stiffness and space
According to Charcoalblue acoustics principal Byron Harrison, the two priorities for the acoustics were a stiff structure and the right spatial arrangement.
‘Our first thought was to understand where there’s dance, because the impact of that movement has the potential to transmit vibration through the whole building,’ he says.
Dance spaces were located at first and second floor level on the side of the building where spans were shorter. This gave a stiffer construction and care was taken not to place them above acting or tv studios. To further avoid movement, the dance studios have floating floors with Sylomer vibration isolation pads from Total Vibration Solutions. These provide a resilient layer and decouple the floor screed from the slab. This discontinuous floor construction also improves acoustic performance to the next door studio by reducing the potential for flanking transmission through the floor.
The strategy for the studio louvres was crucial to the acoustic success of the project. Sufficient acoustic insulation to the exterior was needed while maintaining air flow through the louvres.
There are two external louvres per studio. Charcoalblue and Turner.Works collaborated with manufacturer Mach Acoustic on achieving the optimum solution, which was a fine balance of ventilation requirements and acoustic attenuation. This was delivered using 450mm deep louvres filled with Honeycomb Attenuator, a 3D structure laser cut from acoustic foam. Each louvre is 1140mm wide and 2000mm tall and is clad in plywood with external Corten rainscreen cladding.
For the internal studio louvres, the challenge was avoiding sound leakage that could create a cacophony in the atrium. However some hints of studio activity could be a positive addition to the lively atmosphere of the school.
Respecting the ethos
‘We didn’t want to go too far as the ethos of the building is incredibly creative and the atrium is such a fantastic, vital space. Part of that experience is having bits of music and performance filling it. It was a balance,’ says Harrison.
The solution was a 1m deep louvre full of acoustic baffles to reduce sound leakage into the atrium. Both louvre and attenuators were provided by Gilberts. Such depth meant that these louvres could not be accommodated within the wall. Instead, they project into the atrium and are embraced as part of the industrial aesthetic of the space – the building is conceived as a ‘warehouse for the arts’. Acoustic insulation beneath the atrium walkways was considered but not implemented – in practice, the loudness dissipates upwards. The Academy also contemplated introducing some fabric wall hangings to dampen down the acoustics if it proved necessary, but these haven’t been required.
Within the studios, acoustic rafts with Ecophon Solo panels are used to dampen reverberation and control noise levels. The design team was working towards the Building Bulletin 93 acoustic standards, although a higher acoustic performance was required in the recording studios and main theatre.
The recording studios turned out to be one of the areas that required remedial measures once the Academy was in use. With dance studios located above them and adjacent to the secondary theatre, these were always going to be vulnerable to sound intrusion. The retrofit dealt with this by greatly reducing the number of connections to the slab - just 15 spring hangers are used. Provided by Mason, these are DNHS acoustic ceiling hangers, and were used with three layers of 15mm plasterboard and insulation in the cavity. As well as these measures, independent stud wall linings were introduced.
In the main theatre, acoustic separation was achieved with the use of a separate steel frame to the main concrete structure. Above, a steel truss one floor deep provides storage, with a buffer space between the theatre and an upper level of rehearsal space.
Within the space, Harrison says the aim was to achieve a space that promotes both speech clarity and sufficient loudness. This required sound absorption strong enough to suppress reverberation and aid clarity, but not so much that it would hinder speech projection.
This approach required some hard, reflective surfaces to project sound back to the actors and across the auditorium. These were achieved with balcony fronts and side walls including vertically-slatted timber to the side of the proscenium stage wall. These create architectural interest as well as reducing the harshness of sound that can result from smooth surfaces.
To enhance clarity, sound absorption is provided high above the technical grid on the walls and the rear portion of the ceiling. This is achieved with black Pyrosorb SV-1 porous foam, contained within a protective wire mesh. Noise from the auditorium ventilation is minimised by the use of a slow air flow as it is drawn up from the stalls and through the theatre space.
The main theatre was completed this year after a £1million donation from Cameron Mackintosh, more than a year after the opening of the Studio block. Clad in Corten, the latter is conceived as a visual drape around the edge of the building akin to a theatre curtain.
Turner describes the building as a ‘once in a lifetime project. Building next to Will Alsop’s Peckham Library was a big responsibility,’ he says, adding that he had met Alsop a few times before he died, and that he had been a supporter of the new building.
Client Mountview Academy
Structural engineer Eckersley O’Callahan
Mechanical and electrical engineer Skelly & Couch
Project manager Baqus
Main contractor Gilbert-Ash
Theatre and acoustic consultant Charcoalblue
Gilberts dance studio external and internal louvres and internal attenuators
Mach Products studio external louvre attenuator
Total Vibration Solutions Sylomer studio floating floors
Ecophon studio acoustic rafts
Mason UK DNHS acoustic ceiling hangers