Project: Renovation of roof insulation on the Palais Pálffy, which houses the OSCE headquarters in Vienna
Year built: 1809 – 1813
Roof renovation: 2019
Planning: e f s t u d i o ZT GmbH
Construction firm: Ing. Hans Drascher Ges. m. b. H., Vienna
Because the project is surrounded by very well-preserved, historic buildings right in the heart of the city, non-flammable insulation was the only material acceptable for use. In situations such as this, small spaces and challenging details frequently present major roadblocks to installing traditional materials. CALOSTAT® can help resolve those problems and make optimum use of the limited space available for insulation.
The General Secretariat of the Organization for Security and Co-operation in Europe (OSCE) is headquartered at Palais Pálffy in Vienna’s 1st district. Count Johann Pálffy von Erdöd commissioned the building on Wallnerstraße, which was constructed between 1809 and 1813 on the basis of plans from architect Charles de Moreau. Compared to the Palais Caprara next door, the building makes a rather unassuming, somber impression. Nevertheless, it is considered one of the most significant classicist city palaces in Vienna. An imposing corner structure with a modestly ornate facade, the palace also has a few dramatic rooms, such as the banquet hall from 1818, that have remained intact, despite the building’s many owners and uses.
The building had undergone a general renovation in 2007 and was expanded through an addition in the inner courtyard. The roof, including its insulation, had to be renovated again in 2019, however, as damage had been discovered to the waterproofing layer of the green roof. The insulation installed between rafters had to go as well. Many experts consider laying insulation on top of rafters to be the best, safest way of designing a green roof. Both for this reason and upon the request of the builders, the insulation was installed on the timber deck. This confronted planners with the challenge of working the new insulation packages right up to the existing connection details. Skilled insulation planning on the part of the planning office and coordination with the insulation manufacturer, however, made it possible to fit high-performance CALOSTAT® insulation within the small connection dimensions.
“The fire safety codes in Vienna’s 1st district are strict,” explains Oliver Jung, a civil engineer who supported the project for Evonik. “Only non-combustible materials can be used—at least building material class A2, in other words.” This is why cellular glass insulation, which as a lambda value of 0.037 W/(mK), was used in places with more room. Space was very limited all around the edges, and here builders installed CALOSTAT® Pure (lambda value = 0.020 W/(mK)) in stages, laying one to two layers for a thickness of 40 or 80 mm, respectively. As Jung notes in summary, “Combining two mineral-based, non-combustible insulating materials like this is a good choice for builders. CALOSTAT®’s one-of-a-kind combination of outstanding insulating performance and safety once again makes an exceptional impression. With CALOSTAT®, insulation no longer means having to make compromises—even when space is limited.”
CALOSTAT® Pure 40 was installed on the roof in single or double layers.
The CALOSTAT® Pure boards were covered with bituminous waterproofing membranes , which was followed by application of cellular glass insulation bonded with hot bitumen. The vegetation was then replanted.