Marmo Arte Cultura

	2006 Edition


	by di Vincenzo Pavan

	Pariser Platz 3/Dz Bank by Frank O. Gehry & Associates
	Leibniz Kolonnaden by Kollhoff & Timmermann

FRANK O. GEHRY & Associates - Pariser Platz 3 / Dz Bank, Berlin (Germany)

Extreme stone architecture

The two city facades of the Berlin Pariser Platz complex are an exceptional experience in use of stone materials by contemporary architecture.
The north facade overlooking the historic square, in particular, represents an example of "extreme" stone architecture in the sense that it searches to marry, "at their limits", technology and architectural language in use in a modern construction of a traditional material like stone.
Vicenza Stone, chosen by Gehry for its material and color similarity with the stone used in 1791 by Carl Gotthard Laughans in the Brandenburg Gate, has its own history of great prestige, widely and magnificently used through the centuries by great Veneto architects and in particular by Palladio who used this material in many of his creations. This stone, easy to quarry and dress, is particularly suited for architectural and ornamental components of buildings. It is used in sculpture for exterior statuary, on facades and in gardens. Excellent examples of use in contemporary architecture, in addition to this by Gehry, have been achieved by Mario Botta and by Afra and Tobia Scarpa.

A soft mix of fossils

Vicenza Stone is a soft limestone composed of fossil fragments bonded by a cementing mixture. It has a light straw yellow color with the presence of minute ochre spotting by limonite and goethite.
It is quarried in the Berici Hills (Vicenza), in the zones of S. Gottardo, Costozza, Zovencedo and Grancona. It is very soft when it is just quarried, gradually hardening with time. The warm and luminous surface pigment, if it is left natural, tends to change to gray tones with the passage of time. Three types of Vicenza Stone are quarried for commercial purposes: White, Yellow and Gray. They owe their different colors to the quantity of mineral compounds present in the base mixture.
Frank O. Gehry's Berlin building used Yellow Vicenza Stone coming from Grancona.
The Laboratorio Morseletto Company of Vicenza extracted this material, quarried in tunnel quarries. They use electric power machines with a toothed-chain arm that cuts square blocks with average standard cm. 300x120x100 sizes to cm. 350x450x100 sizes.
Dressing and subsequent installation was commissioned by the General Contractor Müller-Altvatter and performed by the Reinhart Spöttl Pietra International Steinmontagen company.

Pariser Platz 3, south facade

The wall covering of the south facade, on the Behrenstrasse, clad the sawtooth "waves" of profiled concrete with slabs of various sizes of stone. The lower part, corresponding to the base with entries to apartments and garage ramps, used thicknesses ranging between 5 and 8 cm. with maximum 120x150 cm. surface areas. Smaller slabs, with maximum 75x130 cm. dimensions, are used on the rest of the facade containing the ten stories of apartments.
Anchoring was done using Fisher pin techniques with special aluminum alloy brackets. Slabs were installed after the bow-windows were put in place in order to permit correct insulation of the windows themselves.

Pariser Platz 3, north facade

A complex construction system, using "custom" anchor structures, was necessary in order to make the north facade on Pariser Platz. The unusual dimensions of the slabs or, better yet, "monoliths" of Yellow Vicenza Stone (18 cm. thick and maximum 280x420 cm. surface areas) were chosen by Gehry to proportion the facade to the scale of the Brandenburg Gate: with the dimensions of the rocks of the columns, the thicknesses of the cornices, etc.
The impressive size of the slabs required construction of a special block sawing machine (block dimensions varied up to a maximum of 450x350x100 cm.). This process was done in a plant in Verona whereas cutting to size and final dressing was done in Germany.
A special anchor system was designed and produced to install the facade stones. The great weight of the monoliths and the fragility of the stone material, easily breaking at support points and along edges, made slab installation on the facade particularly delicate. This is why a stabilized self-supporting system, generally adapted to "heavy" coverings, was rejected in favor of a special point anchor system with inserts already pre-assembled in the backs of the slabs, exploiting the principle of "light" coverings with thin slabs of stone. This system permits the monolithic slabs to be statically independent from the rest of the covering and also permits independent maintenance (single slabs can be replaced).
A powerful structural framework of large steel sections has been mounted on the reinforced concrete loadbearing structure of the building.First the large single-lite windows were installed on this framework, mounted on sliding steel frames. Then the slabs of Yellow Vicenza Stone where anchored to the outside of the structure, using special cranes and steel anchor dowels with dimensions designed to support the weight of the stone.
The slabs of stone in both facades underwent surface treatment with a silicate filler to protect and maintain the color and luminosity of the stone. All the gaps were puttied with a mixture of substances and pigments with a color like that of the stone.
The "trilithic" motif used to organize the layout of the slabs on the facade combines with the great depth of the windows (an average of 80 cm. from the outer plane of the facade to the disappearing window frame) to generate an overall effect of great and balanced tectonic power: a "monumental minimalism" made even more eloquent by the immaterial appearance of the glazing used for the entryway shelter and the parapets of the "window loggias".
The slabs of Vicenza Stone used to clad the foyer are even larger in size. These, placed on two levels divided by a glass ceiling, have a 280 cm. base dimension and a height of 450 cm. each. These stone monoliths have been reinforced on the hidden side by fastening them to a concrete support that permitted the slabs to be handled during complex interior erection procedures.

Award-winning work at the
International Stone Architecture Award 2003