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A public roof and indoor acoustic comfort: In the Oslo Opera House, the use of RockXolid helped solve the challenge of building a sloping roof you can walk on, while also creating optimal acoustics on the inside.

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Gjerdrums vei 19,
Pb 4215 Nydalen,
NO - 0401 OSLO

Phone: +47 22 02 40 00

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Resembling a glacier and placed right on the water's edge at the Oslo harbour, the Oslo Opera House is an internationally well known architectural landmark. The 38,000 m2 opera building was designed by Norwegian architectural firm Snøhetta and opened its doors in 2007.

One of its most distinct features is the large slanting roof, where the public can walk around, and where machines are able to drive to clear away snow. This posed a special challenge as insulation had to be added to make sure that noises from movements on the roof cannot be heard inside the opera house. "It is right here that one of our products, RockXolid, comes into play. RockXolid has been developed to take the pressure from a concrete floor, rail tracks and trams without changing shape, so the product was perfect for this job," says Project Manager at ROCKWOOL Norway, Trond Olsson.

In fact, the Oslo Opera roof was inspired by the tram in Oslo. ROCKWOOL Scandinavia has previously delivered 11,000 m2 of RockXolid to the company that runs the trams in Oslo, and one of the consulting engineers involved in the Oslo tram projects was also involved in building the Opera. He came up with the "upside down roof" idea, where RockXolid is placed at the bottom.

Resists pressure and keeps out the noise
Håvard Mellem, CEO at Hesselbergtak, who were responsible for roofing, explains why RockXolid was used: "Since the roof is open to the public to walk on, we needed a material that provided good acoustical insulation in order to ensure the quality of the artistic performances inside. RockXolid was chosen because it is sufficiently pressure-proof and also offers good insulation when it comes to noise. Also, drain channels are embedded in the plate, which provides good runoff on the roof membrane."

Håvard Mellem also says that the geometrical design of the roof posed a challenge. 12,000 m2 of marble stones have been added and since they vary in thickness and shape, the thickness of the insulation had to be specifically adjusted to each square metre of the roof. This was solved by using 3D models.

ROCKFON acoustic ceilings also part of the solution
A total of 14,000 square metres of RockXolid was needed. The product was placed under the marble tiles and ensures that no noise from the roof reaches the audience in the Opera. Lars V. Strand, who is a Senior Acoustical Consultant with Brekke & Strand Akustikk, says: "RockXolid gives a combined effect of thermal isolation and noise reduction of footsteps and activities to the sensitive areas below."

The opera house has close to 1,000 rooms and the building has three stages: the Main Stage with approximately 1,400 seats, Stage 2 with up to 440 seats and the Rehearsal Stage 1 with 200 seats. At Stage 2 and in rehearsal rooms, ROCKFON acoustic ceilings are used as part of the acoustics insulation solution. Lars V. Strand explains why: "Apart from being well suited for acoustics insulation, ROCKFON acoustic ceilings also perform well when it comes to fire safety."