Peter Zumthor's Residue: The Bruder Klaus Field Chapel

The Room Was Built First

How Zumthor Made the Bruder Klaus Field Chapel

Zumthor's 2003 study at 1:50, and the tepee of spruce trunks as erected. The idea did not evolve — it arrived complete.

In a field outside Wachendorf, southwest of Cologne, there is a pale concrete tower about 39 feet high with five uneven sides and no windows. You reach it on foot up a farm track. Nothing on the outside tells you what is inside.

It was built between 2005 and 2007 for Hermann-Josef and Trudel Scheidtweiler, farmers who wanted a shrine to Brother Klaus — Nicholas of Flüe, the fifteenth-century Swiss hermit. Zumthor took the job without a fee. The interior is about 215 square feet. There is no power, no water, no heat, no light except the sky.

It is worth studying because the form and the construction method are not two decisions. They are one.

Building the Void

Normally you shape a cavity and fill it. Formwork is a means; it gets stripped and trucked off, and the wall is the product.

Zumthor reversed it. The crew built the room first, full size, out of 112 spruce trunks felled nearby. The logs were stood on an irregular pentagonal footing and leaned inward like a tepee, tips gathering near the top but not closing — that gap became the oculus. Only then was a plywood formwork raised around it in the flat five-sided plan you see from the road.

The inner form is not a mold of the room. It is the room. The wall is whatever got packed into the space left over.

Drawing diagram of construction methods by Chad Schwartz

Two things show clearly in the construction photographs and never make it into the published accounts. First, the tepee is skewed — the logs lean hard to one side and the tips gather off-center, which is why the interior twists as it rises instead of resolving into a tidy funnel. That geometry was set by leaning sticks, not by drawing it. Second, there is rebar standing out of the early lifts. This is not pure rammed mass. Conventional reinforcement is doing the tensile work behind the primitive-technique story.

Midway. The banding is the day count. Note the rebar at the top of the placed work and the triangular door blockout at the base.

Twenty-Four Lifts

The concrete was not a wet pour. It was a stiff, nearly dry mix of local river gravel, reddish-yellow sand and white cement, placed and tamped by hand in the manner of rammed earth. The builders called it rammed concrete. The tradition it borrows from is the regional farm silo, not the job site.

• 24 lifts, each roughly 19-1/2 inches high
• One lift per working day, 24 consecutive days
• Placed by friends and family of the client under a few skilled craftsmen

The horizontal striations on the exterior are not a texture. They are the record of a day's work — twenty-four days of labor, legible at a hundred yards. The building wears its own schedule on its face.

Inner and outer formwork had to be tied against the ramming pressure, and those ties left roughly 350 holes through the finished wall, sleeved in steel tube. Rather than patch them, Zumthor closed each with a mouth-blown glass plug. Inside, in the dark, they read as scattered points of daylight. The detail exists only because the structure required it.

Details of the glass pierced openings as described above

The Chapel's Inner Sanctum

The Fire

With the concrete cured, the wood came out by burning. In autumn 2006 a slow fire was kept alight inside the cone for more than three weeks.

The Chapel's Oculus and Chimney.

Here the sources split, and it is worth being straight about it. The popular account says the logs burned away to ash. The more careful accounts, including the German project documentation, say the fire dried and shrank the trunks so they could be pulled out through the opening at the top, leaving the charring behind. Both produce the same surface. Only one is a plausible way to clear 112 trunks from a 39-foot chimney without wrecking the wall you just built. I would take the second.

What remains either way is a negative: a fluted, blackened cavity carrying the impression of every log — grain, knots, the irregular gaps between them. The soot is not a finish. It is residue. The room still smells of smoke.

The usual comparison is lost-wax casting. Fair, with one difference. In lost-wax the sacrificial material is neutral. Here it is the finish. The wood signs the concrete on its way out.

The Triangular Door

The only opening at grade is a wedge — a steel door about 11-1/2 feet tall and 6 inches thick, set in the shortest of the five faces. The sides run from roughly 10-1/2 to 25-1/2 feet.

The Chapel's Triangular Door

The Chapel's Entry Sequence pierced by triangular light

In the construction photos you can see the door formed as a timber blockout set against the base of the tepee before the first lifts went in. That matters. The wedge is not an opening cut into a wall. It is a piece of the room's own shape reaching out to the exterior.

There are no side hinges. The leaf swings on a single rod cast into the floor, with the bulk of the door cantilevered off that pivot, so opening it means shouldering real weight. Behind it the passage is also triangular in section, and it curves left, so you enter stooped and in the dark and see nothing of the main space until you are several feet in.

The floor is a lead-tin alloy, melted on site and hand-ladled across the concrete. It dishes slightly at the center, under the oculus. The oculus is open, so rain falls 39 feet into that depression and stands there, taking the shape of the opening above it.

The Core of It

Two things about this building seem to contradict each other. The entire design is given over to the interior — and yet the exterior is a monolith you cannot argue with.

The Chapel's triangular door into the monolith

They are the same move seen from opposite sides. The outside has no parts: no joints, no reveals, no trim, no windows, nothing to read as assembly or scale. When a building refuses to tell you how big it is or how it went together, the eye files it as geology — a thing found rather than made. The inside is nothing but evidence of hands: grain, soot, aggregate, glass plugs. The wall is the membrane between those two states, and it is thick enough that crossing it takes a body. That is what the heavy door and the crooked dark passage are for. The compression is not atmosphere. It is the thickness of the argument.

The concrete has no independent existence. It is the residue of the room.

Wright's line, borrowed from Lao Tzu, was that the reality of the building is the space within. Everyone quotes it. Zumthor built it literally: the void first, at full size, in wood you could walk around and touch, and the building assembled around it afterward.

And the room exists because the thing that made it was consumed. A building whose interior finish is the destruction of its own formwork, sitting in a field, dedicated to a hermit. Zumthor added no religious apparatus beyond a small cross above the door, because the construction method already performs the content.

That is the organic argument at full strength. Don't represent the idea. Build it.

Bruder Klaus Field Chapel (Bruder Klaus Feldkapelle), Mechernich-Wachendorf, Germany. Peter Zumthor, consecrated May 19, 2007. Open to the public, free, on foot.