Project Name: Garnet Chapel, Penkenjoch
Membrane: Rhepanol fk
Architect: Mario Botta
Contractors: Robert Stadlmeyer GMBH & Co
To provide durable weather protection of the chapel, a high-quality polyisobutylene based (PIB) synthetic roof waterproofing was installed behind the CorTen steel sheets.
The Garnet Chapel is designed by Mario Bott and faces north towards the Ziller Valley below. It is built on a concrete base and consists of twelve rhombuses made of 120mm thick plywood panels. On the outside, the façade is clad with 300mm wide CorTen steel sheets at 10mm spacing. The steel sheets rest on a total of 2,280 threaded rods anchored in the supporting structure. The façade alone weighs 17 tons and the supporting structure adds another 4 tons.
Local Specialist Roofing Contractors Robert Stadlmeyer GMBH. & Co. carried out the waterproofing works. They installed the tested and proven premium roofing membrane Rhepanol fk made by German manufacturers FDT. The membrane is equipped with an integrated synthetic fleece and a prefabricated self-sealing edge. Flexibility at temperatures as low as minus 60oC significantly facilitate material handling of the membrane, and even in extraordinary weather the membrane features outstanding stability and durability highly favourable for such a location.
Rhepanol fk also has environmental benefits and an extremely long lifespan in use. The environmental profile indicates that Rhepanol fk is a permanently UV and ageing resistant synthetic roofing membrane and also does not contain any plasticizers or halogen fire proofing agents. An independent life cycle assessment according to ISO EN 14040-49 showed that neither the raw materials, nor the product process or the processing and long-term use of Rhepanol fk cause any significant environmental impact. Even after its useful life the membrane can be fully recycled.
Although only 412 square meters of roof and façade needed waterproofing, this task turned out quite challenging for the roofers. Aside from the demanding site-specific logistics extraordinary weather conditions, like snow in the middle of August, had to be considered.
To prevent wind uplift, the membranes were bonded in strips to the supporting timber structure with the permanently elastic synthetic rubber based FDT roofing membrane adhesive.
Once the initial waterproofing was carried out, the threaded rods to support the CorTen steel cladding were anchored in half of the elements still lying on the ground. In order to achieve quick, accurate and permanently waterproof flashing against the rods, the roofers employed a preformed detail perfectly adapted to the roofing membrane: the FDT lightning conductor sleeve with Rhepanol collar.
While one half of the structural panels had their threaded rods fitted on the ground, the remainder where attached and waterproofed when the panels were in place using a scaffold.
Upon complete installation of the elements, the corners were additionally secured with special nail boards. Then the roofers sealed the 14 corners and 24 edges with Rhepanol cover tape and Rhepanol sealing tape. At this point chapel was then completely weather proof, ready for installation of the steel supports and the CorTen steel sheets.
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