The Dirt on a Restaurant Bar Built of Rammed Earth

Architecture firm BÜRO KLK renovated the bar of Mochi, a well-known Japanese restaurant in Vienna, Austria that it originally designed in 2012. The brief was to maintain "the original, vivid character of the place while optimizing the spatial situation with regard to current needs."

The architects write:

"The geometrically pleated counter block made from rammed earth, realized by Martin Rauch, Austrian pioneer in rammed earth building techniques, is the dominant design element. In the context of sustainable building, this ancient building material, deeply rooted in the tradition of the Near East, has regained importance in the past years."

Rammed earth is a Treehugger favorite. As we note in our explainer on rammed earth, "The name says it all: it’s made of damp soil or earth that is placed in formwork, and then compressed or rammed into a solid, dense wall."

There are two kinds: raw, which is carefully mixed clay, sand, silt, and water; and stabilized, where some kind of binder (usually cement) is added to hold it together. Martin Rauch, the master of raw rammed earth, who refuses to mix in cement told The Architectural Review:

"Interfering in the material properties of loam is detrimental. One thus takes away its most important characteristic, since the material can only be integrated into the cycle of materials again without admixtures. When being dismantled, the wall once again becomes the earth from which it came. This is absolutely essential."

It gives new meaning to the term "raw bar"

Fewer buildings or interiors have shorter lives than restaurants, so a raw rammed earth bar makes perfect sense, it is the ultimate raw bar. BÜRO KLK confirms it is in fact built without stabilizers, telling Treehugger: "Martin Rauch did not add any cement for stabilization. The counter is placed on a 10mm steel plate, that’s all. It came in four parts that were pieced together on-site. In total, the counter has a weight of four tonnes."

Raw rammed earth's enemy is water, which is why when Rauch designs buildings like his own house shown here in Treehugger, he added stone "horizontal cornices" that projected out to keep water off the wall, as well as "dry feet and a good hat"—foundations and roof overhangs. You don't see much raw rammed earth in North America, thanks to dubious building inspectors and freeze-thaw cycles. But in a restaurant? You could probably get away with that.

It does appear that this has a good hat of what looks like a form of terrazzo, cantilevering off to the left side; you can't do that with dirt.

Rauch must have been pleased not to worry about that inside a restaurant, where the only problem would be a spilled bowl of miso soup or sake, or perhaps cleaning staff who are a bit over-eager. Although he must have been worried about moving four tonnes of the stuff, it is remarkable that it didn't arrive as a pile of dirt.

Here is a close-up of the terrazzo top, where you can see the stones in it, ground smooth. This project is more of a geology and construction class than a restaurant.

The beauty of rammed earth comes from the way you can layer different colors and types of soil. This is all pretty consistent, but you can see the lines between each roughly 4-inch layer. But the real beauty of Rauch's rammed earth is the fact that there is no stabilizer, no cement. That's what makes it really Treehugger correct.

As architectural critic Phineas Harper wrote in The Architectural Review:

"Compacted soil is a beautiful material, its striations echoing the strata of the Earth’s crust, but depending on how you use it, it can harm, as well as evoke, the planet. There is no need to build rammed earth with cement... Some designers, however, are choosing the humble aesthetic of earth, and its ecological connotations, but without the sincerity to follow through those values on the construction site."

BÜRO KLK is a young firm that describes itself as "an interdisciplinary office in the field of tension between architecture, design, planning and consulting. By exploring space, material, construction, and their interplay, BÜRO KLK creates aesthetic places that shape our perception of space and social interaction." When Treehugger covered the firm's "highrise of huts" project, it attracted some criticism for not being very green at all. The Mochi renovation, made of perhaps the greenest material on earth, is certainly a different interplay of materials.