i ce hotels present many challenges to their designers. First-time visitors, expecting to see a structure made of ice blocks, are surprised that the building is actually a series of cast-in-place snow vaults. The construction process begins with manufacturing the snow. Artificial snow is used because of the demands of the construction schedule for a ready supply of pure white snow of consistent quality. Also artificial snow is less dry than natural snow, which helps it freeze into place more solidly. The next step is the placing of the vault moulds.As many as eight moulds may be placed in line at a time.The moulds used in the first ice hotel done by Émile Gilbert + associates in 2001 were imported from Sweden, home of the original ice hotel. These roman arch-shaped moulds were manufactured in sections to facilitate shipping. As a consequence, vaults built using the original moulds were marred by horizontal lines where the sections join together. The roman arch, while structurally sound in theory, proved to be subject to severe deflection, requiring shoring up with ice block columns. To eliminate these two problems, a second series of moulds was pro- duced in Quebec for the 2002 hotel.The new moulds were made of two continuously curved stainless steel sheets that join at the apex of a gothic arch, eliminating horizontal joint lines and making a more stable vault. The roman arches continued to be used, in this case, for the chapel. Had the chapel had been built with gothic arches, we suspect it would not have sagged as much, despite the warm weather. Each mould is 8 feet deep and between 15 and 20 feet wide, depending on the model. An ice hotel, although it presents a monolithic appear- ance, is actually a modular building. Spaces listed in the design program are given in terms of number of moulds required, simplifying the initial diagrammatic phase of design, but complicating circulation during design development. The hotel is divided into two sections; circulation through the public section is through the main vaults themselves, which include the lobby, two galleries, and the bar. The use of courtyards resolves some circula- tion problems, and the addition of longitudinal corridors (formed with a new, third type of mould) for access to the 35 guestrooms and suites further alleviated the situation in 2002. In 2003, circulation was refined with the addition of transverse, hand-built corridors crossing the larger vaults between guestrooms. After the moulds have been placed for the first series of vaults, snow is sprayed onto the vaults with a snow cannon to a thickness of 4 feet at the sides and 2 feet at the apex of the vault. The process is very similar to the gunite process for spraying concrete. Once the wet snow has hardened into opaque ice (24-48 hours) the moulds are slid down the line to form the next series of vaults. Ice columns are placed inside the fresh vaults and ice block walls are built at the exposed ends. South- facing vault ends are particularly vulnerable to the sun, and the ice walls help prevent them from drooping. Icy surfaces: the Duchesnay Ice Hotel Karl Loeffler
24
O n S ite review
S urface
I ssue 9 2003
Made with FlippingBook interactive PDF creator